U.S. Rep. Bruce Braley’s said Monday that he has raised more than $1 million since Sen. Tom Harkin announced at the end of January that he wouldn’t run again for the Senate.

Braley, a Democrat who represents Iowa’s 1st Congressional District, made it known shortly afterward that he would run to succeed Harkin, and he’s been busily picking up labor union endorsements over the past few weeks. The new fundraising number will be a further reminder, if one is necessary, that he’s the clear front-runner for the party’s nomination for the 2014 race.

In an email Monday, Braley said the campaign had “smashed” its end-of-quarter fundraising goal. He said he had raised more than $1 million since Harkin’s announcement.

Harkin’s decision surprised Iowa politics watchers and has set off a scramble of speculation to see who might replace him. So far, Braley is the only one to say definitely that he’s in the running.

On the Republican side, U.S. Rep. Steve King, R-Iowa, has said he’s considering a bid, but it’s not clear when he might make an announcement. U.S. Rep. Tom Latham, R-Iowa, has said he won’t run.

Braley’s campaign had not release details of his fundraising haul Monday. But his two months of fundraising compares favorably to other high-profile campaigns over the past decade.

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Republican Rep. Greg Ganske raised $829,000 in the first six months of 2001 for his 2002 bid against Harkin. Roxanne Conlin, a Democrat, raised $609,000 in the last three months of 2009, although she didn’t fully get into the race until the quarter was partially over. Conlin was seeking to unseat Sen. Chuck Grassley, R-Iowa, in the 2010 election cycle.

In his email to supporters, Braley said the fundraising totals are helping the campaign to build a strong organization across the state.