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Senate Democrats on Wednesday blocked a bill that would crack down on Syrian and Iraqi refugees coming to the U.S. as the debate turned into a referendum on Republican presidential candidate Donald Trump and his policies.

Senate Democrats sought to force election-year votes as Trump — who holds a commanding lead in national polls for the Republican presidential nomination — has called for barring Muslims from coming to the United States. Republicans wanted similar votes on politically fraught amendments.

The Senate fell short of the three-fifths needed to move ahead. The vote was 55-43.

The House legislation would require new FBI background checks and individual sign-offs from three high-ranking federal officials before any refugee from Syria or Iraq could come to the United States. The American Security Against Foreign Enemies Act cleared the House in November in the aftermath of the Paris attacks. It received 289 votes, a veto-proof margin that included 47 Democrats — despite President Barack Obama's opposition.

"This bill is just another step in the absolute wrong direction, the direction of Donald Trump," Reid told reporters before the vote. "The Democrats are committed to opposing the hateful views of Trump and his Republican enablers."

But Senate Republicans who backed the House bill said it is difficult to effectively vet immigrants from war-torn countries like Syria and Iraq, where record keeping is poor — or may not exist at all. They also said senior U.S. intelligence and law enforcement officials have expressed concern that the Islamic State may try to exploit the refugee screening program.

"So it is any wonder that the citizens we represent are concerned?" McConnell said. "No wonder dozens of Democrats joined with Republicans to pass this balanced bill with a veto-proof majority over in the House."

Three of the Republican presidential candidates — Ted Cruz of Texas, Marco Rubio of Florida and Rand Paul of Kentucky — left the campaign to return to Washington to vote for moving ahead on the measure.

Democratic presidential candidate Bernie Sanders of Vermont missed the vote as did Republican Sen. Lindsey Graham of South Carolina, who was campaigning for Jeb Bush in New Hampshire.

Two Democrats from GOP-leaning states — Heidi Heitkamp of North Dakota and Joe Manchin of West Virginia — voted with Republicans to move ahead on the legislation.

For Democrats facing tight 2016 elections, opposing the bill may put them in the difficult position of rejecting what many consider to be a reasonable anti-terror measure in the wake of a terrible tragedy. Those concerns surfaced ahead of the House vote in November when White House aides went to the Capitol to win over Democrats in a private meeting. Rep. Sean Patrick Maloney, D-N.Y., told them, in a forceful exchange, that voting "no" could hurt Democrats at the polls, according to aides in attendance.

In addition to the amendment on Trump, Reid said Democrats also wanted to propose an increase in anti-terrorism money for local police forces and airport security and banning the sale of guns and explosives to people on federal terrorism watch lists.

This House bill, Reid said, "scapegoats refugees who are fleeing war and torture instead of creating real solutions to keep Americans safe."

House Speaker Paul Ryan, R-Wis., said the bill is a security test, not a religious one. "This reflects our values," Ryan said. "This reflects our responsibilities."

Cruz announced Tuesday he was canceling two events in New Hampshire and rescheduling two others in order to return to Washington to vote. While Republicans said the bill contains no religious tests for the refugees, Cruz and White House rival Jeb Bush have suggested giving preferences to Christians.

Obama has scolded politicians for raising worries over taking in refugees fleeing the Islamic State's harsh rule in Syria and Iraq, where it controls territory. "Apparently, they're scared of widows and orphans coming into the United States of America," Obama said when the House voted last year. The White House has said Obama will veto the legislation if it reaches his desk.

Voters' concerns about terrorism have surged at the same time their confidence in the government's ability to defeat IS and other extremist groups has plummeted, according to a national survey conducted in December by the Pew Research Center.

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AP writer Donna Cassata contributed to this report.

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Follow Richard Lardner on Twitter at http://twitter.com/rplardner

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