WASHINGTON -- Relatives of victims of the horrendous Connecticut school shootings are mounting a face-to-face lobbying effort Tuesday in hopes of turning around enough lawmakers to gain a Senate floor vote on meaningful gun restrictions as Senate Democrats approach a key decision on gun legislation.

Their effort follows President Barack Obama's remarks in Connecticut on Monday night on gun control, an issue catapulted into the national arena by December's gruesome slaying of 20 young children and six educators at the Sandy Hook Elementary School in Newtown, Connecticut.

"If you want the people you send to Washington to have just an iota of the courage that the educators at Sandy Hook showed when danger arrived on their doorstep, then we're all going to have to stand up," the president said.

Obama's proposals -- headlined by background checks for more gun buyers and bans on assault weapons and high-capacity ammunition magazines -- have hit opposition from the nation's powerful gun lobby, the National Rifle Association, and are struggling in Congress. Conservatives say they will use procedural tactics to try preventing the Senate from even debating firearms restrictions.

Underscoring the high emotional stakes, some Newtown families are in the Capitol lobbying senators to support gun restrictions, including 11 relatives Obama ferried back to Washington on aboard Air Force One after his speech.

The administration was continuing its efforts to pressure Republicans, with Vice-President Joe Biden and Attorney General Eric Holder making remarks Tuesday at the White House, joined by law enforcement officials.

Senate Democrats, meanwhile, are approaching decision time on whether they should try to get Republican support for expanding background checks for firearms sales or will follow the shakier path of pursuing the cornerstone of Obama's gun control effort on their own.

Democrats were holding a lunchtime meeting Tuesday to assess whether to seek a compromise with Republicans or try the shakier path of trying to advance a gun control bill over opposition objections.

Party leaders were giving Democratic Sen. Joe Manchin until later Tuesday to complete the talks with Republican Sen. Pat Toomey and see if they could reach an acceptable compromise.

An agreement between the two senators, both among the more conservative members of their parties, would boost efforts to expand background checks because it could attract bipartisan support. Abandoning those negotiations would put Democrats in a difficult position, making it hard for them to push a measure through the Senate and severely damaging Obama's gun control drive.

The administration was continuing its efforts to pressure Republicans, with Vice-President Joe Biden and Attorney General Eric Holder making remarks Tuesday at the White House, joined by law enforcement officials.

Majority Leader Harry Reid brought gun control legislation to the Senate floor on Monday, though actual debate did not begin. He took the step after receiving a letter from 13 conservative Republican senators who said they would use delaying tactics to try to prevent lawmakers from even beginning debate on the legislation. Such a move takes 60 votes to overcome, a difficult hurdle in the 100-member chamber.

Further underscoring the tough road ahead for the Obama-backed legislation, a spokesman for Senate Minority Leader Mitch McConnell said that he would join the effort to block debate on the legislation if Reid tries to bring the measure to the floor.

There are 53 Senate Democrats and two independents who generally vote with them, meaning Republican support ultimately will be needed to reach 60 votes to move ahead.

The conservative senators said the Democratic measure would violate the Second Amendment of the U.S. Constitution which guarantees the right to bear arms, citing "history's lesson that government cannot be in all places at all times, and history's warning about the oppression of a government that tries."

"Shame on them," responded Reid. "The least Republicans owe the parents of those 20 little babies who were murdered at Sandy Hook is a thoughtful debate about whether stronger laws could have saved their little girls and boys."