* Issue has dogged Warren since April
* "I am who I am," Warren says
By Tim McLaughlin
BOSTON, Sept 20 (Reuters) - Massachusetts Republican Senator Scott Brown slammed Democratic challenger Elizabeth Warren's claim she is part Cherokee as they squared off in a televised debate on Thursday in one of the country's most closely watched U.S. Senate races.
Brown called on Warren, a high-profile liberal supporter of President Barack Obama, to release her personnel records from Harvard University to prove she did not gain any unfair advantage as an ethnic minority when the college hired her in the 1990s.
Warren is trying to regain a seat - which Brown won by an upset in 2010 in a special election following the death of Democratic liberal stalwart Edward Kennedy - that would help the Democrats retain their slim majority in the U.S. Senate.
Accusations that Warren may have received special breaks because she claimed Cherokee ancestry first surfaced in April, dogging the Harvard Law School professor and former Obama administration official and giving Brown a way to challenge her integrity.
"As you know ... Professor Warren has claimed she is a Native American, a person of color. As you can see, she is not," Brown said in their first of four TV debates before the Nov. 6 election.
Brown characterized Warren as being disingenuous about her heritage.
"I didn't get an advantage because of my background," Warren replied. "I can't change who I am. I am who I am."
Warren said she was told as a child that her mother had Native American roots. "When I was growing up, these are the stories I knew about my heritage," Warren said. "I never asked anybody for any documentation. I don't know any kid who did."
Inside the studios of WBZ-TV in Boston, Brown kept pressing the issue, saying all she needed to do was to release her personnel records to show what box she checked for describing her heritage.
WARREN LEADS IN POLLS
Brown's salvo came on the heels of two polls released this week that gave the lead in the race to Warren, chief architect of the Consumer Financial Protection Bureau, which was established after Wall Street banks buckled during the 2008 financial crisis.
She got a political bounce from a fiery speech at the Democratic National Convention, while women voters continue to favor her over Brown by a comfortable margin, said Peter Ubertaccio, chairman of Stonehill College's political science and international studies department.
"Republicans had no bounce from the GOP convention and their brand continues to be very unpopular here," Ubertaccio said.
Brown has been working to put distance between himself and Republican presidential candidate Mitt Romney, a former Massachusetts governor.
He has rejected Romney's comment that disparaged 47 percent of Americans as victims reliant on federal aid. Romney made his remark in May at a private fundraiser in Florida. A secretly recorded video of the fundraiser surfaced on Monday
During the debate, Warren cast herself as a champion of the working class and criticized Brown for voting against three jobs bills in a row in the Senate.
"I want to go to Washington to fight for jobs," she said.
Known for his pickup truck, good looks and moderate views, Brown caught Massachusetts' Democratic machine napping when he emerged from obscurity to beat Martha Coakley, the state's attorney general, in the 2010 special election.
Ubertaccio said Brown's attack on Warren over the ethnic heritage issue was a "dangerous" move.
"Voters really moved by that are very likely already with him," Ubertaccio said.