Massachusetts’ Senatorial candidates square off

>>> savannah, thanks. now on the trail and the high profile and expensive senate ration in massachusetts . i moderated a pretty tough debate between the candidates last night, and nbc's capitol hill correspondent kelly o'donnell was there as well. kelly , good morning.

>> reporter: good morning, david. it was must see here in massachusetts . this is the most expensive senate race. $53 million being spent by just the candidates who agreed to have no outside groups involved. now, there were thousand inside the arena, and many more outside here outside. the clash was loud.

>> go, scott brown .

>> reporter: and sometimes angry outside.

>> you're delusional!

>> reporter: inside the arena a tense duel between republican senator scott brown and harvard professor democrat elizabeth warren .

>> excuse me, i'm not a student in your classroom, please let me respond, okay? thank you.

>> reporter: led by moderator of "meet the press" david gregory who took on the candidates' nasty running battle and campaign ad war.

>> professor warren got caught in a lie.

>> reporter: whether warren used her native american heritage to gain any employment advantage with law school .

>> do you consider yourself a minority?

>> i listed myself as native american . i was listed there. it's part of who i am.

>> reporter: brown argues that warren has not told voters why she switched between calling herself native american on applications.

>> she changed her nationality to native american .

>> reporter: and later referred to herself as white.

>> at the pinnacle of her success when she became tenured at harvard she changed back to being white.

>> are you hiding something?

>> no, i'm not. i never used it for college, for law school or to get a job.

>> reporter: to appeal to democrats who far outnumber republicans here, brown calls himself an independent thinker who works with president obama .

>> of course i'm going to be proud to stand with the president. he is our president, and when he does something well, i praise him.

>> reporter: but warren hit brown for raising money by tying his re-election to republicans gaining control of the senate.

>> when senator brown talks here in massachusetts about how very bipartisan he is and how very independent he is, he's sure not saying the same thing when he goes around the country raising money.

>> reporter: both candidates made awkward stumbles. warren was asked to name a republican senator she could work with.

>> probably richard lugar would be one to come to mind.

>> reporter: indiana's dick lugar is actually retiring.

>> that is a problem.

>> reporter: and brown , who is a lawyer, appeared unprepared for this.

>> who is your model supreme court justice ?

>> after touting bipartisanship brown first named an ultra conservative.

>> let me see here. that's a great question. i think justice cascalia is a very good judge, justice kennedy .

>> reporter: and for warren it's a challenge because massachusetts has never elected a woman to the senate or as governor. for brown , with his big election year turnout in a presidential year, it may be tougher for him as a republican. david?

>> kelly o'donnell at umass lowell . thanks very much.