WASHINGTON -- U.S. President Donald Trump sought comfort in the figurative embrace of his evangelical supporters Thursday as the FBI director he recently fired told Congress about their conversations. The president told a religious gathering that "we're under siege" but will emerge "bigger and better and stronger than ever."

Trump made no reference to James Comey in his remarks to the Faith and Freedom Coalition's annual gathering. But hours before the president's first public comments of the day, Comey told the Senate intelligence committee that Trump tried to get him to pledge loyalty and drop an investigation into former National Security Adviser Michael Flynn.

Trump abruptly fired Comey last month. Trump's attorney said the president never asked Comey to stop investigating anyone.

In his remarks to the conference, Trump pledged to always support the right of evangelicals to follow their faith, which some conservatives believe is under attack by government.

"We will always support our evangelical community and defend your right and the right of all Americans to follow and to live by the teachings of their faith," the president told more than 1,000 activists meeting at a hotel across town from Capitol Hill, the scene of Comey's nationally televised testimony.

"And as you know, we're under siege, you understand that. But we will come out bigger and better and stronger than ever. You watch," Trump said. "You fought hard for me and now I'm fighting hard for all of you."

Trump spoke about his actions to safeguard religious freedom and continued, for the second straight day, to label congressional Democrats as "obstructionists" who are blocking his agenda. Yet it is differences of opinion among Republicans, who control both houses of Congress, that are standing in the way of what Trump wants to do on health care and other issues.

Trump mentioned his nomination of federal judge Neil Gorsuch to the Supreme Court, which pleased Christian conservatives. He also has directed the IRS to ease up on using a rarely enforced rule barring partisan political activity by churches and tax-exempt organizations.

"As long as I'm president, no one is going to stop you from practicing your faith or preaching what is in your heart," he said.

Trump won an overwhelming 80 per cent of the white evangelical vote in the November election. A recent Pew Research Center survey marking his first 100 days in office found three-fourths of white evangelicals approved of his performance as president. Thirty-nine per cent of the general public held the same view.

Trump said restoring freedom also meant repealing and replacing the health care law enacted in 2010 by then-President Barack Obama, saying high deductibles and premiums have turned it into a "catastrophe." But a replacement health care bill has yet to clear Congress despite seven years of pledges by Republicans to scrap the law and start over, and despite the fact that the GOP has full control of the White House and Congress.

The Republican-controlled House passed a bill with the bare minimum of GOP votes and none from Democrats. Senate Republicans are working on their version of the bill, but are divided about the approach.

Trump overlooked the intraparty squabbles and blamed Democrats. He said Democrats have gone so far to the left in terms of opposing him that "they're bad right now for the country." Democrats oppose dismantling Obama's health law.

The president urged the audience to help send more Republicans to Congress in next year's midterm elections, noting the GOP has just a 52-48 edge in the Senate and a slim advantage in the House.

"We have to build those numbers up because we're just not going to get votes" from Democrats, he said. "Sadly, we're going to have to do it as Republicans because we're not going to get any Democrat votes and that's a very, very sad, sad thing."

Trump ignored the fact that three Democratic senators voted to put Gorsuch on the Supreme Court.

Associated Press writers Jonathan Lemire in New York and Vivian Salama in Washington contributed to this report.