A new Mass Insight poll in Massachusetts shows Sen. Scott Brown (R-MA) leading challenger Elizabeth Warren (D), 52% to 42%.

Key finding: “While 58% thought it was good for the state to have ‘an independent Republican like Scott Brown representing us in Congress,’ and 39% disagreed, voters were clearly begrudging about watching Republicans retake the Senate. Forty-nine percent thought the state needed to elect a Democrat to prevent the chamber from going Republican, 47% disagreed.”

In response to a question about gun control today, Mitt Romney claimed he owns guns himself.

Said Romney: “I believe in the second amendment, I’ll protect the second amendment, I have guns myself. Not going to tell you where they are. Don’t have them on myself either, alright.”

However, ABC News reports that in 2007, “after Romney claimed that he did have guns he later retracted his statement, saying that he himself does not have guns but his sons do.”

Just published: Defeat at Waterloo: Fighting on the Front lines of the Hillary Clinton Presidential Campaign by Amanda Wilkerson.

Former Sen. Bob Kerrey (D-NE) announced today that he would run for U.S. Senate, “setting the stage for a competitive election year in Nebraska as Democrats fight to retain the seat and Republicans battle to take it back,” the Omaha World Herald reports.

“Kerrey acknowledged that his thought-making process may have been unconventional — he initially said he was out, then said he was in — but he ultimately decided he wanted to be a part of the national debate.”

Said Kerrey: “Doing things the conventional way has never been my strong suit. This afternoon, I will file to become a candidate for the United States Senate in Nebraska. I came to realize that my previous decision was the easy one, not the right one.”

“I gotta press the button. That will be my heavy lift in terms of manufacturing.”

— Mitt Romney, quoted by the Washington Post, while touring a family-owned fence-post maker in Ohio.

A new Middle Tennessee State University poll shows Rick Santorum way ahead in next week’s Tennessee GOP primary with 40%, followed by Mitt Romney at 19%, Newt Gingrich at 13% and Ron Paul at 11%.

First Read: “The biggest impact of Romney’s narrow victory in Michigan: It silences the talk of a white knight riding to the GOP’s rescue. While such an outcome might not have occurred even if Romney lost — was a Christie/Daniels/Jeb Bush really going to jump in this late in the game? — last night pretty much closed the door on that kind of speculation, even if Romney struggles next week on Super Tuesday (which is entirely possible).”

But Michelle Cottle disagrees, saying “don’t look for the dream to die anytime soon. Mitt Romney’s win wasn’t pretty and will continue to fuel concerns that the GOP electorate, despite its visceral hatred of Obama, won’t be as fired up as it needs to be to kick ass in November.”

Steve Kornacki notes Sen. Olympia Snowe’s (R-ME) retirement was a huge gift to Democrats.

“A pickup in Maine would alter the playing field nationally, where Democrats can survive a net loss of three seats and still retain control of the chamber (if Obama is reelected, with Vice President Joe Biden breaking a 50-50 tie). The party is facing potential losses in Virginia, North Dakota, Nebraska, New Mexico and elsewhere, with only two obvious pickup targets (Massachusetts and Nevada) — until now. If there is a second term for the Obama White House, Snowe may end up being a lot more helpful to it than she was in the first term.”

First Read says Snowe’s exit “gives Democrats a better than 50%-50% chance of holding the Senate in November. If Democrats win in Maine and Massachusetts, then they’ve moved the bar to Republicans needing to win five seats (if Obama loses) and six (if he wins). We can see how Republicans get to four (North Dakota, Nebraska, Montana, and Missouri). And we can see how they maybe get to five (adding Virginia or Wisconsin or Ohio). But six? That would mean that Republicans would need to win in a New Mexico or a Florida or a Michigan.”

Sean Trende: “We’re finally close enough to Super Tuesday to get a sense of how the overall delegate count might work out in the GOP primary. The end result: Assuming that none of the four candidates drops out of the race, it looks increasingly as if no one will be able to claim a majority of the delegates. The candidate with the best chance is Mitt Romney, but he probably wouldn’t be able to wrap up the nomination until May or even June. The other candidates will probably have to hope for a brokered convention.”

Rep. David Dreier (R-CA) announced on the House floor that he will not seek re-election, The Hill reports.

Said Dreier: “We all know that this institution has an abysmally low approval rating, and the American people are asking for change in Congress, and so I’m announcing today that I will leave the Congress at the end of this year.”

Los Angeles Times: “Dreier is the sixth California House member to announce his
retirement when his term expires, further shaking up a delegation that
has built up clout on Capitol Hill because of its stability over the
years.”

Maine GOP strategist Matthew Gagnon says Sen. Olympia Snowe’s (R-ME) “reason for taking a pass on re-election, especially when she was so enthusiastically running up to this point, and especially as close to the filing deadline as this is, are mysterious. As I said before, this kind of thing does not happen in politics.”

“I am told her own staff was unaware of this decision until just hours before the statement went out — just long enough to actually work on the release and send it out.”

Maggie Haberman: “This is a bit of a problem for a movement candidate: Ron Paul, whose strategy has been to amass delegates through a caucus-focused strategy, has become essentially an afterthought because of the way he is now viewed.”

“Theories abound as to what’s driving this. Among them: Paul wants his voice heard at the convention; he’s trying to get his son Rand on the ticket; he’s working to ensure Rand’s future in 2016. Whatever the reason, the narrative is taking root that Paul is essentially in this to take down Romney’s rivals, as he airs negative ads against them and siphons off votes. His aides vigorously deny this, but the claim is being repeated enough that it has overshadows the role Paul once played in the race.”

Interestingly, Paul goes on the air today with a new ad in Washington state that hits all three of his rivals.

Peter Hamby notes “the mechanics of the 2012 Republican race are beginning to resemble those of the 2008 Democratic nomination fight, a grind-it-out battle for delegates that could last through well into the spring.”

“Romney continues to lead his foes in the delegate hunt, adding at least three dozen to his total after beating Rick Santorum in Michigan and Arizona. But with 437 delegates on the table next Tuesday, and with most of them allocated according to each candidate’s share of the vote, all four of the GOP contenders are certain to boost their delegate counts, giving everyone in the field a rationale, however thin, to move forward.”

BuzzFeed: “Mitt Romney’s presidential campaign has far-outraised his opponents, but that doesn’t mean he’s flush with money. With a sky-high burn rate, and running out of rich donors to tap, Romney made an appeal for small-dollar donors tonight after winning the Michigan and Arizona primaries — his first direct appeal for money at a non-fundraising event in recent memory.”

Meanwhile, the Wall Street Journal says some Romney allies say he “may have to write a check from his own personal fortune to tide over his campaign.”