WASHINGTON (Reuters) - Republican presidential hopeful Mitt Romney is expected to report raising between $15 million and $20 million in campaign cash for the quarter ending on Thursday, a campaign aide said, a sum that far outpaces rivals.
Romney's dominance in the money race stems from his relentless campaigning and fund-raising since he lost a presidential bid in 2008. In addition, several of his rivals have only just entered the race.
Aides to rival Jon Huntsman, who formally announced his candidacy on June 21, said on Thursday he had taken in about $4 million in recent weeks, with a bit less than half coming from his own pockets.
Romney, a former Massachusetts governor, is the front-runner in the Republican race to replace President Barack Obama in the 2012 election. He leads most polls of party rivals and has more than enough money to stay competitive.
"He is raising money far more quickly than he can spend effectively, especially in Iowa and New Hampshire where retail politics is important," said Georgetown University government professor Clyde Wilcox.
Romney rivals like Huntsman and Tim Pawlenty must raise enough to remain competitive, he said.
"If you don't have enough money, volunteers and fund-raisers may start wandering," he said, adding that "enough" may be a matter of surpassing expectations.
The second-quarter figures have not been officially released for the campaigns.
Some outside experts had predicted Romney would raise between $20 million and $30 million, especially after a one-day haul of $10 million last month.
A senior Romney adviser said the totals are in line with what they planned, but also cited "economic headwinds," which could depress fund-raising.
Meanwhile, Pawlenty is struggling in the polls and being overshadowed by the entry of rising Tea party star Michele Bachmann into the race.
"She's clearly stealing oxygen from him in terms of Iowa," University of Minnesota professor Larry Jacobs said.
Pawlenty's advisers have been trying to downplay expectations since the former Minnesota governor entered the race.
"Our numbers are going to be respectable but it's not going to blow (anything) out of the water," said Ray Washburne, national finance chair for Pawlenty's operations in Texas.
Bachmann, a conservative member of the House of Representatives, is an adroit fundraiser. Her congressional committee out-raised all of her House colleagues during 2010, with a $13.5 million haul.
The campaign to re-elect Obama had a goal of raising $60 million, between the campaign and an account at the Democratic National Committee, in the quarter ending on Thursday.
In addition to Romney's official figures, a new so-called Super political action committee created by former Romney aides is said to have pulled in at least $10 million, according to a report in the Wall Street Journal.
These are a new form of political action committee created after a federal court decision last year allowed unlimited contributions from corporations and unions to independent political committees.
Additional reporting by Steve Holland and Todd Melby; Editing by Xavier Briand