(CBS News) In one of the most costly and closely-watched Senate races of the electoral cycle, another big-name politician is entering the fray.
New York City Mayor Michael Bloomberg is throwing his weight behind Massachusetts Republican Sen. Scott Brown, who is being challenged for re-election by liberal consumer advocate Elizabeth Warren.
Bloomberg, a moderate who is not affiliated with either major party, will hold a fundraiser for Brown on August 15 in New York City, Brown's office confirmed. Tickets to the fundraiser will cost between $1,000 and $5,000 per person.
"Mayor Bloomberg is a true independent who always puts progress over politics. That's Scott Brown's philosophy as well, and he is honored to have the Mayor's support," Brown campaign spokesperson Alleigh Brown told CBSNews.com.
(Bloomberg's recent appearance on "Face the Nation.")
Bloomberg is just the latest in a string of high-profile figures to get involved in the contest: In May, Boston-bred celebrities Matt Damon and Ben Affleck hosted a fundraiser on Warren's behalf.
President Obama, too, has voiced his support for Warren, whom he tapped to head up the Consumer Financial Protection Bureau in 2009.
The heavily Democratic state is viewed as a key opportunity for Democrats to pick up a Senate seat, and a Democratic victory there could be pivotal in the party's efforts to maintain control of that chamber. But Brown, who won the seat in a 2010 special election following longtime Sen. Ted Kennedy's death, has developed a strong base of support among moderate and conservative Democrats, and has stressed to voters his willingness to break with Republicans on certain issues. Warren, meanwhile, has been dogged by accusations that she improperly identified herself as Native American in order to further her professional career.
Both parties have been relentless in their attacks, with Brown casting Warren as a member of the Harvard political elite, and Warren painting Brown as beholden to Wall Street and the wealthy.
In recent days, Brown has seized on a national debate over comments President Obama made suggesting that people who have built successful businesses have usually benefitted from government aid of some sort, arguing that Warren gave Mr. Obama the idea.
"The president got bad advice from professor Warren, certainly," Brown said in a Thursday appearance on Fox News, referencing similar comments Warren has made in the past. "You'll never hear me demonizing our job creators."
Warren, on the other hand, is blasting Brown over his Thursday vote against a Senate bill extending Bush-era tax cuts for middle-class voters but ending them for those earning more than $250,000 per year.
"Washington should be cutting taxes for middle class families, not protecting tax breaks for billionaires," Warre said in a Thursday statement. "Scott Brown's got it all wrong - again -- voting to hold tax cuts for the middle class hostage so he could protect tax breaks for billionaires. Now was the time to stand with working families in Massachusetts but Scott Brown said 'no'."
Recent polling suggests that the race will go down to the wire. Political spending in the state, meanwhile, has been overwhelming.
According to a review of Federal Election Commission reports, this year's Massachusetts U.S. Senate candidates have raised more money in this race than any other in state history, raising a combined $46.7 million as of June 30.