U.S. Republican presidential candidate Donald Trump speaks at a campaign event at the Veterans Memorial Building in Cedar Rapids, Iowa, December 19, 2015. REUTERS/Scott Morgan

WASHINGTON (Reuters) - Donald Trump would win a hypothetical head-to-head contest against either of his two closest Republican U.S. presidential rivals, Ted Cruz and Marco Rubio, but he would fall short of beating Democratic front-runner Hillary Clinton if the election were held today, according to a Reuters/Ipsos poll on Monday.

If the Republican primary featured a face-off between Trump and Cruz, a Texas senator, Trump would win the support of 41 percent of Republican and independent voters, the poll showed. Cruz would take 31 percent, while 28 percent said they would not vote in a Cruz-Trump contest.

If Rubio, a Florida senator, were pitted against Trump, the billionaire real-estate mogul would take 40 percent support of Republican and independent voters to Rubio’s 34 percent, according to the poll. Twenty-seven percent said they would not vote. In this matchup, Trump’s lead over Rubio is within the survey’s credibility interval.

Cruz and Rubio currently sit in second and fourth place of all Republican candidates, respectively, in the run-up to the November 2016 presidential election, according to a Reuters/Ipsos poll on Friday.

Despite months of leading the Republican polls, Trump would fall short in a general election competition held today against Clinton, the poll showed. In a one-on-one match-up, the former secretary of state would take 40 percent support of all voters to real estate mogul Trump’s 29 percent.

Eight percent of respondents said they did not know which candidate they would support in a Clinton-Trump competition. Fourteen percent said they would not vote for either one, and another 9 percent said they would not vote at all.

The survey of 1,627 likely voters from all parties was conducted between Dec. 16 and Dec. 21, with a credibility interval of 2.8 to 3.7 percentage points.