The long-heralded race for the Republican presidential nomination is set to begin this week as a multitude of potential candidates for the job of taking on President Barack Obama in 2012 head to the first key battleground state of Iowa.

Five potential runners will appear tomorrow at an event organised by the Iowa Faith and Freedom Coalition in the state capital, Des Moines. They include big names such as former House speaker Newt Gingrich, former Pennsylvania senator Rick Santorum and former Minnesota governor Tim Pawlenty, as well as outsiders such as the Tea Party favourite, businessman Herman Cain.

In a sign of how serious the race has now become, Santorum, a darling of the religious right with extremely conservative views on social issues, will spend this week touring all the early voting states of Iowa, New Hampshire and South Carolina in a trip that bears all the signs of a genuine campaign swing.

Santorum's move throws down the gauntlet to other potential candidates, including former Alaska governor Sarah Palin, who must now consider jumping into the fray to stop other candidates soaking up early publicity. The race is set to dominate the political headlines for all of 2011 and be one of the most hard-fought and intense in recent memory.

In many ways, that could be good for Obama, who will sit back and watch his Republican opponents forced to attack each other. "With a long primary season these candidates are going to go after their rivals. They will do a lot of Barack Obama's work for him," said Professor Shaun Bowler, a political scientist at the University of California at Riverside.

It will also make for fascinating politics as the Republican field fills out with a ragtag mix of current and former politicians who run the range from potentially serious contender to joke candidate. At the moment the leader in recent polls is Mike Huckabee, the current Fox News host and former governor of Arkansas, who won Iowa in 2008 before eventually losing the nomination to John McCain. Huckabee last week created headlines by appearing to criticise Obama for his family links to Kenya and spending part of his childhood in Indonesia. Such statements create bad mainstream press but appeal to the Republican base. Huckabee is now setting the pace with many Republican experts. "I think Huckabee is in a tremendous position, certainly in Iowa. He will do very well there," said Steve Mitchell, chairman of political polling firm Mitchell Research.

Huckabee has started to outshine the man tipped early on to be the Republican front-runner: former Massachusetts governor Mitt Romney, who has been hit hard by criticism that a healthcare plan he applied in his state was too similar to Obama's reforms. With the Republican party campaigning vigorously to have healthcare reform repealed, Romney's prospects have been dampened.

He is not alone in having major image problems in important areas. Indeed, almost all of the Republican field has at least one major drawback, which could provide a boost for Obama and his Democrat team. Candidates like Huckabee, Santorum and Gingrich are seen as conservative enough to win a Republican primary but very off-putting to more moderate independent voters who will probably decide the 2012 election.

More centrist figures, such as former ambassador to China Jon Huntsman, lack name recognition and are unpopular with the Republican base. Some candidates, like Pawlenty and Indiana governor Mitch Daniels, are seen as competent but also bland and uninspiring. Meanwhile, Mississippi governor Haley Barbour is seen as being too Southern to appeal outside that region and has sullied his chances with a series of insensitive remarks on race.

There are also novelty candidates, such as the oft-touted presidential ambitions of reality TV businessman Donald Trump, or Tea Party stars Cain and congresswoman Michele Bachmann, whom few see as remotely serious.

Finally, looming above it all, is Sarah Palin. Though she has a fanatical fan base and huge fame, the former governor of Alaska is seen as a wildly divisive figure. She is polling badly among Republican voters and many experts feel that her work as a speaker and author is too lucrative for her to risk what would be an intense and lengthy campaign. However, if she were to jump in she would be likely to electrify the race and the nation.

That means that many experts should see Obama as a favourite to win. However, he faces a great challenge in the form of an economy that is struggling to emerge from recession, especially in the area of job creation. Some experts see the 2012 race less as Obama vs a Republican and more as Obama vs the economy.

Many believe that, if the economy is still in trouble 18 months from now, Obama could potentially be defeated by almost any Republican candidate. "If the economy is still stuck in the summer of 2012, then Obama will be vulnerable. But if the economy clicks, then Obama wins," Bowler said.