WASHINGTON -- The Republican-controlled Senate acquitted U.S. President Donald Trump on two impeachment charges Wednesday amid Republican complaints about what they called a rushed process and Democratic claims that Trump is a threat to democracy. The historic, three-week trial proceeded largely along partisan lines, with just one senator -- Republican Mitt Romney of Utah -- breaking with his party.

Takeaways from just the third impeachment trial of a president in U.S. history:

TRUMP'S IRON GRIP ON GOP

Some Republican senators expressed reservations about Trump's conduct; some even went so far as to say that House Democrats successfully made their case against him. Nonetheless, Trump's acquittal was never truly in doubt in the Senate. Even Republicans who disapproved of Trump's dealings with Ukraine -- the heart of the House impeachment charges -- said his conduct did not merit making him the first president ever removed from office.

In ways unimaginable when he was first elected as a political newcomer, Trump has come to utterly dominate the GOP. Republican lawmakers bow to his overwhelming popularity with the party's base. "It's not a party of ideas or ideology anymore. It's a cult of personality," tweeted Sen. Chris Murphy, D-Conn.

Republicans insisted they were acting in the interests of their constituents and their conscience, and they reacted with outrage when Democratic Rep. Adam Schiff, the lead impeachment manager, cited a media report claiming that a person close to Trump had warned Republicans their "head will be on a pike" if they voted against the president.

Trump has already shown his power to cast out dissident Republicans. Former Sens. Bob Corker of Tennessee and Jeff Flake of Arizona decided not to run for reelection rather than face voters after clashing with Trump.

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McCONNELL DELIVERS -- AGAIN

Senate Majority Leader Mitch McConnell. R-Ky., again proved himself Trump's most important ally. He led a drive to deny Democrats any opportunity to call witnesses before the Senate and worked closely with the White House in shepherding the case to acquittal, fulfilling a pledge he made before the trial to "take my cues from the president's lawyers."

McConnell slammed House Democrats' drive to impeach Trump as "the most rushed, least fair and least thorough" in history. He said the two impeachment charges against Trump -- that he abused his power and obstructed Congress' ensuing investigation -- are "constitutionally incoherent" and don't "even approach a case for the first presidential removal in American history."

Senate Democratic leader Chuck Schumer of New York accused McConnell and his GOP colleagues of sweeping Trump's misconduct under the rug. "The administration, its top people and Senate Republicans are all hiding the truth," Schumer said, adding that Trump tried to "blackmail a foreign country to interfere in our elections."

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PROVEN, BUT NOT IMPEACHABLE

Republicans voted to acquit Trump, but many wanted to be on record as frowning on his conduct. Perhaps the most prominent example was retiring Sen. Lamar Alexander of Tennessee, who voted against hearing from witnesses but called out Trump's actions as "inappropriate."

Other Republicans followed suit, insisting that their votes against witnesses or in favour of acquittal should not be interpreted as approval of his actions.

"I do not believe that the House has met its burden of showing that the president's conduct -- however flawed -- warrants the extreme step of immediate removal from office," said Sen. Susan Collins, R-Maine.

"Our country is already too deeply divided and we should be working to heal wounds, not create new ones. It is better to let the people decide," added Sen. Rob Portman, R-Ohio.

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ROMNEY STANDS ALONE

In an unlikely twist, Romney, the GOP's unsuccessful 2012 presidential nominee, was the only Republican senator to break ranks in the impeachment trial and favour removing Trump from office. The well-mannered, patrician Romney stood alone in his vote to oust a Republican president who seldom hides his contempt for the senator and the establishment Romney symbolizes.

Romney's support for removing Trump on a charge of abuse of power also denied Trump's campaign a frequent talking point of asserting that he had full support of Republicans in the House and Senate during a strictly partisan drive to remove him.

Romney voted to acquit Trump on the second article of impeachment, obstruction of Congress, joining his 52 GOP colleagues.

Romney, a Mormon, cited his religious faith and the significance of the impeachment oath taken by senators to render "impartial justice" on impeachment. "The grave question the Constitution tasks senators to answer is whether the president committed an act so extreme, so egregious, that it rises to the level of a high crime and misdemeanour," Romney said in a floor speech. "Yes, he did."

GOP Sen. Steve Daines of Montana called Romney's vote "very disappointing," adding: "I strongly disagree. But he has to speak for what he believes."

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DEMOCRATS UNITED

Throughout the trial, the votes of at least three Democrats were uncertain. Sens. Joe Manchin of West Virginia, Kyrsten Sinema of Arizona and Doug Jones were all considered possible votes to acquit Trump. Manchin even floated censuring Trump instead of removing him from office, though the idea did not gain much traction. In the end, all 47 Democrats voted to find Trump guilty on both articles of impeachment.

Manchin, a former governor and a rare Democrat holding office in the nation's most pro-Trump state, said he could explain his vote for removal based on the evidence that was presented. "There was no other conclusion that I could come to, as much as I knew how divisive it would be, as difficult as it would be," Manchin said. "It's based on, could I go home ... and face my family, my friends and the good Lord that I swore to?"

Jones, whose seat in ruby-red Alabama is in jeopardy, said impeachment has been partisan from the beginning and the country needs to figure out how to move forward together. A former federal prosecutor, Jones won a special Senate election in 2018. He said he had not thought about how his votes to convict Trump might affect his reelection chances, saying simply he was comfortable with his decision.

Sinema said in a statement that she was upholding her duty to the Constitution and putting the interests of the country ahead of partisan politics or personal interest.

"The facts are clear; security aid was withheld from Ukraine in an attempt to benefit the president's political campaign. While White House attorneys claim this behaviour is not serious, it is dangerous to the fundamental principles of American democracy to use the power of the federal government for personal or political gain," she said.

White House lawyers also failed to assure the American people that future national security decisions will be made free from personal interests, Sinema said. "That should be gravely concerning to all of us."

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REVELATIONS NOT OVER

The end of the Senate impeachment trial won't bring an end to revelations about Trump's dealings with Ukraine. There are books to be written and documents being withheld by the administration that could ultimately become public.

Former national security adviser John Bolton writes in a book due out next month that Trump tied the suspension of military aid to Ukraine to investigations that Trump wanted, just as House prosecutors alleged. The Justice Department disclosed in a court filing last weekend that it has 24 emails related to Ukraine that it has not produced.

Additional disclosures are possible from witnesses who testified in the House impeachment inquiry and may feel emboldened to share even more now that the president has been acquitted. Or witnesses unknown to the public could step forward.

Democrats are fighting to release grand jury testimony from special counsel Robert Mueller's Russia investigation and for the testimony of ex-White House lawyer Don McGahn.

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THAT WAS QUICK

Whether rushed or not, the impeachment was the fastest impeachment ever. The House voted to impeach Trump a week before Christmas, less than three months after Pelosi launched the impeachment inquiry.

After a four-week delay while Democrats pressed for rules changes to extend the trial, House Democrats carried the formal articles of impeachment against Trump to the Senate in mid-January.

Three weeks later, the Senate voted to acquit Trump without new testimony or subpoenas.

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LET VOTERS DECIDE

Many senators who voted to acquit Trump said they were disappointed in his conduct or disapproved of it, but that it was up to voters to decide Trump's fate in November.

Alexander said House prosecutors had proved the charges against the president, but said they didn't rise to an impeachable offence.

"The question is not whether the president did it," but whether the Senate should decide what to do about it, Alexander said last week in becoming the decisive vote against witnesses and documents. "I believe the Constitution provides that the people should make that decision in the presidential election."

Sen. Lisa Murkowski, R-Alaska, called the president's actions "shameful and wrong." But she said the proper response to Trump's behaviour was "not to disenfranchise nearly 63 million Americans" -- who voted for Trump in 2016 -- by removing him from the ballot.

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FOREIGN INTERFERENCE PERMISSIBLE?

An already ill-defined area of law may be even murkier for 2020 campaigns, thanks to an answer on foreign election interference from deputy White House counsel Patrick Philbin.

Democrats pressed Trump's legal team to acknowledge that foreign election interference is not only wrong but also illegal. Asked if Trump agreed that foreign involvement in an American election is against the law, Philbin pointed out that the law only covers foreign campaign contributions or other so-called things of value. The Justice Department concluded for that reason that Trump's call with Ukraine's leader didn't violate campaign finance laws.

Democrats called Philbin's statement shocking. "The single most important lesson that we learned from 2016 was that nobody should seek or welcome foreign interference in our elections," said Rep. Hakeem Jeffries, D-N.Y., an impeachment manager. "But now we have this president and his counsel essentially saying it is OK."

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LEGAL ARGUMENTS ARE POLITICAL

Trump's lawyers, including retired Harvard law professor Alan Dershowitz and former independent counsel Ken Starr, presented a variety of arguments to senators. They said Trump never made military aid contingent on investigations. They painted him as beset by biased investigators and asserted that even if he did what he was accused of, it still wasn't impeachable.

In the end, though, the argument that appeared to resonate most with senators was inherently political: impeaching a president in an election year, the argument went, invites chaos and instability, upends the will of the voters and opens the door to future presidents being tossed from office on partisan whims.

"They are asking you to tear up all of the ballots across this country, on your own initiative -- take that decision away from the American people," White House counsel Pat Cipollone said.