Conceivably, Brown's announcement is a harbinger of a different Senate dynamic come January. While the news media stresses the narrative of a hopelessly divided Washington in this looming mid-term election, a less-known development will go far to shape politics in 2011 and beyond: Republican moderates are making a comeback.

Yes, Tea Party activists have toppled several incumbents, dealing a blow to establishment party politics, but conservatives still hold the vast balance of power within the national party.

Come January, however, the Senate should have a healthy infusion of moderate blood at the Senate's swearing in. Scott Brown typifies the coming shift. A Tea Party darling when he defeated heavily favored Massachusetts Democratic Attorney General Martha Coakley, Brown was known for his populist bent.

He drove a truck across the state during the campaign and railed against President Obama's health reform. He vowed in his stump speeches to give the people a stronger voice in an increasingly out-of-touch Washington, running against the notion that the seat vacated by Kennedy was somehow owned by the Massachusetts Democratic Party. Republican policymakers and analysts unanimously began to refer to him as the "41st vote."

His campaign was a spectacular success. The virtually unknown state senator harnessed and galvanized a conservative uprising in the unlikeliest of states. He energized his supporters to vote for him in a special election, and took the seat held for decades by Senate liberal lion Edward M. Kennedy. Yet, as The New York Times has pointed out, Brown has governed so far as a quintessentially Republican Northeastern moderate. His positions are more Collins and Snowe than Inhofe and DeMint. His recent indication that he would vote for the financial services reform bill solidifies that characterization.

Why? Brown faces re-election in 2012, and he knows that strictly toting the GOP line on financial reform, for instance, will weaken his re-election prospects among the still-not-conservative Massachusetts electorate. He has a strong political incentive to embody centrist pragmatism and tread lightly on the more fiery politics of partisan opposition on high-profile legislative issues.

There is, of course, a healthy tradition of GOP moderates, a tradition not entirely lost on Scott Brown. It has waned in recent decades, but it isn't dead. There are few Rockefeller Republicans — not completely anti-government, environmentally conscious and willing to work with their Democratic colleagues — left any more. Brown, however, is clearly drawing upon the venerable tradition of Republican Northeastern pragmatists, who tended in the 1960s, '70s, and '80s toward liberal stances on social issues, supported a strong national defense, and weren't uniformly averse to wielding federal power to advance economic equality.

Brown is his own man, of course. His politics aren't a carbon copy of Edward Brooke (MA), William Weld (MA), or Nelson Rockefeller (New York). But Brown has firmly planted himself in a more moderate camp within the GOP. In January, he will likely be joined by more GOP moderates in the Senate. In addition to Maine's two senators, Susan CollinsSusan Margaret CollinsOvernight Energy: Trump NASA pick advances after drama | White House office to investigate Pruitt's soundproof booth | 170 lawmakers call for Pruitt to resign Trump's NASA nominee advances after floor drama Family, friends mourn death of Barbara Bush MORE and Olympia Snowe, Michael Castle of Delaware, Carly Fiorina of California and Mark KirkMark Steven KirkHigh stakes as Trump heads to Hill Five things to watch for at Trump-Senate GOP meeting Giffords, Scalise highlight party differences on guns MORE of Illinois appear to have serious shots at winning their respective Senate elections. Charlie Crist of Florida, running as an independent, could serve as a seventh member of an informal GOP moderates caucus. With 60 being the magic number in the Senate to secure passage of controversial bills, even four or five GOP moderates could hold the balance of power in the post-midterm election environment.

Cameron Lynch is a former aide to three U.S. senators and the president and founder of The Lynch Group LLC. Matthew Dallek, a visiting scholar at the Bipartisan Policy Center, teaches history and politics at the University of California Washington Center.