Washington (AFP) - The Republican-controlled US Senate rejected four competing gun control measures Monday just days after the Orlando club massacre, highlighting the partisan feuding over an issue set to resonate during a heated presidential election year.

With a month to go before Republicans and Democrats formally nominate their White House hopefuls, lawmakers failed to compromise on one of the most sensitive hot-button issues in America.

Even as they sought to appear keen to take action following the deadliest mass shooting in US history that left 49 dead at a gay nightclub in Orlando a week ago, Republicans and Democrats voted down four amendments -- two from each party -- that would have limited some gun purchases, including those by suspected terrorists.

The two Democratic texts sought to bar those on FBI watchlists or no-fly lists from buying firearms, and to strengthen criminal and mental health background checks for those seeking to purchase firearms at gun shows and on the Internet.

Republicans are opposed to those measures -- in general, they oppose any effort to limit gun rights, saying they are protected by the US Constitution's Second Amendment.

They proposed a 72-hour waiting period for those on FBI watchlists seeking to buy weapons, so that the government has time to seek a court order to block the sale if need be.

The second Republican proposal aimed to improve the background check system. Democrats rejected both GOP measures.

Such efforts often struggle to pass the Senate, where 60 of 100 votes are needed for legislation to advance.

The Senate voted on similar measures in the wake of the December 2012 Connecticut school massacre and the San Bernardino attacks last year, but to no avail.

"Every single senator wants to deny terrorists access to guns they use to harm innocent civilians, but there's a right way to do things and a wrong way," said Republican Senator John Cornyn of Texas.

Number two Senate Democrat Dick Durbin was livid at the failure of lawmakers to come together on such a pressing issue after yet another shooting.

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"Tonight, the Senate turned its back on victims of gun violence from Orlando to San Bernardino, from Newtown to the streets of Chicago," Durbin said in a statement.

There are 46 senators who are Democrats or generally vote with Democrats, and 54 Republicans.

Susan Collins, a moderate Republican senator from Maine, was expected to unveil some kind of compromise legislation, but it also seemed unlikely to pass.

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Presumptive Democratic presidential nominee Hillary Clinton has spoken out at length about the need to curb gun violence in the week since the Orlando tragedy, but she had a shorter message Monday.

"Enough," she said in a one-word statement, followed by the names and ages of the 49 Orlando victims.

Democrats know they have only a slim chance of succeeding with gun reform ahead of the November elections. Their goal for now is to push the debate on guns -- and turn it into a true campaign issue.

"Ultimately, the only way that you win this issue is by building a political infrastructure around the country that rivals that of the gun lobby," Democratic Senator Chris Murphy told ABC's "This Week" show on Sunday.

Last week, Murphy mounted a 15-hour filibuster on the Senate floor that prompted Republican leaders to schedule Monday's cloture votes.

"Our filibuster helped galvanize an entire country around this issue," he said.

Republican presidential hopeful Donald Trump made waves last week when he suggested he would meet with the National Rifle Association -- which has endorsed him -- to push a ban on weapons sales to those on watchlists.

On Sunday, Trump said the NRA was seeking to defend "the best interests of our country," adding: "They want to make the right decision."

Since the attack on the Pulse nightclub in Orlando, Trump controversially said he only wished more of the people in the club had guns to defend themselves.

But the NRA's executive vice president and chief executive Wayne LaPierre contradicted Trump, saying: "I don't think you should have firearms where people are drinking."

Trump has since walked back his comments, tweeting that he was "obviously talking about additional guards or employees."