The most expensive U.S. Senate race in the country appeared even more costly Monday when U.S. Senator Scott Brown and Harvard Law School professor Elizabeth Warren announced that they had raised $7.45 million and $12.1 million, respectively, in the third quarter of 2012.

The totals from July, August, and September bring the candidates’ combined total for the race to more than $60 million. Warren, who has been the best-financed Congressional candidate in the country this year, has now raised a total of more than $36 million. Brown has raised a more modest $27.4 million, but he started the race with $7 million left over from his 2010 special election run for the Senate. Both campaigns have received millions of dollars from out-of-state donors.

The high fundraising totals and out of state donors point to the race’s national prominence this election year. The Bay State seat is seen as a crucial battleground in the fight for control of the U.S. Senate.

But with Election Day only three weeks away, political strategists say the campaigns’ fundraising success in the past has lessened the potency of money as the race winds down.

“The amount of money [Warren] raised in the last quarter is astounding, but what is also amazing is how little the money can buy these candidates in the last three weeks,” said Republican political consultant Todd Domke. “There’s only so much TV or radio time they can buy.”

As cash declines in significance, the presidential race has unexpectedly risen in importance, Domke said. Though Obama is still expected to win Massachusetts in a landslide, former Mass. Governor Mitt Romney’s strengthening poll numbers have raised new questions about Obama’s prospective margin of victory in the Commonwealth. If that margin narrows, Brown will likely pick up the former Obama supporters and may have enough to support to upset the Democratic Warren, Domke said.

“It comes down to this external factor. And partly that’s because Warren’s [campaign] is much more invested in riding Obama’s coattails than winning on her own,” he said.

Democratic political strategist Mary Anne Marsh said that the breakdown of donation numbers—which have only been released in summarized form—provides important insight into the campaigns’ respective supporters.

“Fundraising is the truest measure of support before the votes are cast,” she said. “It tells you who really supports a candidate...especially in a close race in the home stretch,” Marsh wrote in an email to The Crimson. She could not be reached by phone.

Brown’s campaign said 60 percent of his donations came from within Massachusetts. Warren’s campaign said that 53,000 Massachusetts donors have contributed and 80 percent of the camp’s donations were $50 or less.

—Staff writer Nicholas P. Fandos can be reached at nicholasfandos@college.harvard.edu.