Republican candidate Ted Cruz has kicked off tonight's Iowa debate by mocking his opponent Donald Trump and suggesting he has shown a lack of respect to voters by not showing up.
"I'm a maniac and everyone on this stage is stupid fat and ugly and Ben you're a terrible surgeon.
Now we've got the Donald Trump portion out of the way I want to thank everyone here for showing the men and women of Iowa the respect to show up.
Donald Trump's foundation has raised more than $5 million (£3.5m) for veterans ahead of a rally he is holding during the Republican debate in Iowa.
Ahead of Thursday night's event, the billionaire said he would be donating $1m of his own money to the fund and that many of his wealthy friends would also be contributing.
Trump launched a website, donaldtrumpforvets.com, collecting donations for the cause on Thursday.
He is boycotting the final GOP debate because of a feud with host Fox News.
US Republican party presidential candidates are preparing for a key debate in Iowa this evening which is going ahead despite current front-runner Donald Trump's refusal to attend.
Texas Senator Ted Cruz, Florida Senator Marco Rubio, former Florida Governor Jeb Bush, New Jersey Governor Chris Christie, Ohio Governor John Kasich, Kentucky Senator Rand Paul and retired neurosurgeon Ben Carson will all take part in the debate.
Trump has opted out of the chance to take part instead choosing to host his own event nearby.
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President Barack Obama has conceded that the Republican party has had a "good night" after they secured a majority in the US Senate in last night's midterm elections.
He said that the message from last night was that voters want to see the Washington gridlock eased.
Watch Obama's press conference at the White House:
Republicans stormed the Senate and House of Representatives in the US Midterms, claiming all of Congress for the first time since 2008.Read the full story ›
As well as claiming a victory in the Senate, Republicans were expected to extend their lead in the House of Representatives to 246 seats to 189, give or take six seats.
NBC News' political director Chuck Todd says such a lead would make it unlikely that the Democrats could retake the House before the year 2022.
A Republican majority in the Senate could make President Barack Obama's remaining time in office much more difficult, as Kate Fisher reports from Washington: