New Jersey Governor Chris Christie became the latest out-of-state politician to lend a hand in the hard-fought Massachusetts U.S. Senate race on Wednesday, when he endorsed U.S. Senator Scott Brown at a rally in Watertown.

Speaking through a megaphone held by Brown, the firebrand New Jersey Republican called Brown an independent, open-minded leader who would not “posture and pose” along party lines like those who have forced Washington into gridlock.

“If you all like what’s going on in Washington, D.C. right now, if you like the divisiveness, if you like the fact that most of those folks down there don’t know how to work across the aisle, don’t know how to solve real problems...then you’ve got the perfect choice on the ballot for that candidate. You should vote for Professor Warren,” Christie said, referring to Brown’s Democratic opponent, Harvard Law School professor Elizabeth Warren.

“She won’t even look across the aisle, let alone reach across the aisle,” Christie added a few moments later. “And yet, you’ve got a Senator here who has served this state extraordinarily well by making sure that he talks to Republicans, Democrats, Independents, everyone.

”Christie, who is thought to be a rising star in the Republican party, linked his own political career to Brown’s, explaining that his own 2010 gubernatorial inauguration coincided with Brown’s special election victory in Massachusetts and ushered in a new style of Republican bi-partisanship.

“We have been connected ever since,” Christie said.

Endorsements like Christie’s are not uncommon for a Senatorial candidate, especially one entrenched in a tight race that is thought to have national importance. The New Jersey Republican is the latest in a growing group of out-of-state politicians who have swooped into the Bay State to bet their chips on either side of the Massachusetts U.S. Senate race in recent weeks.

U.S. Senator John McCain (R-AZ) used his national importance to boost Brown’s candidacy at a rally here on Oct. 20. Leaning on his own political capital and incorporating flares of his characteristic humor, U.S. Senator Al Franken ’73 (D-MN) spent much of last weekend firing up volunteers and voters on the campaign trail with Warren. The Democratic candidate had also previously received support from former U.S. Senator Max Cleland (D-GA).

Massachusetts is one of a handful of swing states that could determine which party has a majority in the Senate starting in January. A WBUR poll released Monday by MassINC Polling group showed Warren up by five points, leading Brown 48 percent to 43 percent. The poll, which surveyed 516 likely voters from Oct. 21 to Oct. 22, had a 4.4 point margin of error, indicating that the race is still close.

The endorsements and campaign trail appearances reflect what robust out-of-state financial donations have long suggested: Republicans and Democrats across the country are willing to go a long way to see their party win this Senate seat.

To what degree out-of-state endorsements will make a difference is unclear. While party leaders are well positioned to excite voter bases, they may not sway independent voters, especially if the endorsements are expected, said Democratic political strategist Dan Payne.

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