Republican presidential candidate Donald Trump greets guests before speaking at a campaign event on January 23, 2016 in Pella, Iowa. PHOTO: AFP

WATERLOO, UNITED STATES: One might be forgiven for forgetting that there are 12 Republicans still in the White House race — for now, it's a two-man show.



The battle between billionaire frontrunner Donald Trump and maverick Senator Ted Cruz is the main event for conservatives, who are torn with nine days to go before the Iowa caucus.



The two candidates are dominating the polls ahead of the February 1 caucus in the small heartland state, the first to vote in the US presidential nominations process, and both made appearances here on Saturday.



The latest opinion poll, conducted by CNN among likely Republican voters, shows Trump with 37 per cent support to 26 per cent for Cruz. Florida Senator Marco Rubio follows with 14 per cent. The margin of error is six percentage points.



At the start of January, several polls had Cruz in first place. The 69-year-old real estate tycoon Trump and the 45-year-old Texas senator refused to attack each other until just recently. But Trump now calls his chief rival "a nasty guy" and a hypocrite for slamming New York values while taking money from donors in the Big Apple.



The two men are vying for support from the same people: the voters farthest to the right of the political spectrum — the target for the primaries. On Saturday, Trump started the day in Sioux Centre in northwest Iowa.



Cruz "could run for the prime minister of Canada, and I wouldn't even complain because he was born in Canada," Trump said, repeating that Cruz's birthplace could disqualify him from the race, though many experts say the opposite.



The Texas senator, meanwhile, was joined on the Iowa trail on Saturday by conservative television and radio host Glenn Beck, who offered his official endorsement. "We need a new George Washington," Beck said.



Instant reply from Trump? "Glenn's a loser," he said. "I wouldn't do his show so he got very hostile," Trump noted, praising his loyal supporters. "I have the most loyal people. I could stand in the middle of Fifth Avenue and shoot somebody and I wouldn't lose any voters, okay?"



And when Beck joined Cruz later Saturday at a rally in Waterloo, Iowa, both took shots at the New York real estate mogul, who famously said at a recent presidential debate that he was "angry" about the direction of the country.



"Many of us are angry. You never make a good decision when you're angry, it will not end well if we play into the anger," Beck said.



Cruz has portrayed Trump as an unscrupulous businessman who favors seizing private property so his casinos can thrive. The senator accuses the tycoon of being an opportunist with no real attachment to conservative values.



In part, Cruz owes his success to his intransigence in the Senate, where he has steadfastly refused to make any compromises with Democrats. This ideological fervour should in theory help him win over evangelical Christian voters — who make up about 60 per cent of the Republicans who cast ballots in 2012.



Evangelicals are very conservative on social issues, opposing abortion and same-sex marriage, and defending the role of religion in society. They helped boost Mike Huckabee and Rick Santorum to victory in Iowa in 2008 and 2012.



"It would be hard for a Republican in Iowa to win without at least some support from them," Dennis Goldford, a professor of political science at Drake University in Des Moines, told AFP. "Ted Cruz is trying to prove that you can win with them alone."



The rest of the Republican party has watched amazed, powerless and divided as the anti-establishment candidates have powered along, with party leaders seemingly unable to contain them. Traditional Republican candidates like Jeb Bush, whose father and brother have both served as president, have fallen by the wayside in the polls.



This week, the National Review, a venerable conservative magazine, launched a special issue "Against Trump," calling on fellow Republicans to reject his candidacy.



"Trump is a philosophically unmoored political opportunist who would trash the broad conservative ideological consensus within the GOP in favor of a free-floating populism with strong-man overtones," it said in a biting lead editorial.



"There are understandable reasons for his eminence... but he is not deserving of conservative support in the caucuses and primaries." The broadside triggered an angry response from the Republican National Committee, which disinvited the National Review from being a partner of the party's candidate debate on February 25.



Some party stalwarts however have welcomed Trump. Former New York mayor Rudy Giuliani told The Washington Post that he preferred Trump to Cruz. Veteran senator Bob Dole, the party's presidential candidate in 1996, has the same opinion.



They seem to think Trump's cunning opportunism will be an advantage come November, because the tycoon will have no problem changing up his positions to attract wider support.