Senate Republicans are more committed than ever to opposing President Barack Obama’s health care agenda, citing a GOP victory in the Massachusetts special election as validation of their political strategy and policy course.

State Sen. Scott Brown (R) defeated Massachusetts Attorney General Martha Coakley (D) Tuesday in the battle to succeed the late Sen. Edward Kennedy (D). Republicans early in the day said Brown didn’t even need to win to stiffen the GOP’s resolve and prove that they have been on the right side of the health care debate — a close race would be proof enough.

Top Republicans said Brown’s performance in the overwhelmingly Democratic Bay State confirms public surveys showing wide discontent nationally with the Democrats’ leadership and policies, and they remain confident that success in the upcoming midterm elections hinges largely on their opposition to health care.

“The American people all over the country are opposed to the bill. They don’t want it passed,— Senate Minority Whip Jon Kyl (R-Ariz.) said. “There’s no way you can spin it as not a referendum on health care — as well as other issues — but clearly on health care.—

Over several weeks toward the end of 2009, the 40-seat Senate Republican Conference remained unified in its opposition to the Democrats’ $871 billion health care reform package — forcing Majority Leader Harry Reid (D-Nev.) to round up the support of all 60 Members of his caucus to pass the bill.

As Democratic leaders work to reconcile the Senate bill with the $1.2 trillion House version approved before Thanksgiving, Republican opposition has held firm.

In the wake of Brown’s surprising surge in the contest to replace Kennedy — perhaps Congress’ biggest champion of health care reform over the past half-century — Republicans feel as though opposing Obama on this and other issues poses virtually no political risk.

The GOP was already preparing an aggressive messaging strategy on health care for this week, seeing the issue as a political winner even as it appeared powerless to block final passage. Feeling as bold as at any time since Obama was inaugurated one year ago, the minority is now poised to press the Democrats and the White House on myriad issues — health care among them.

“There is no end to the empirical evidence that Republicans have taken the correct course on health care. The political landscape has fundamentally changed so radically that the most liberal state in the union could be on the precipice of electing a Republican,— a senior GOP Senate aide said Tuesday, before the polls had closed. “The president and Democrat leaders have walked their entire Conference off a cliff. Since all 60 Senate Democrats voted for health care, seats that have no business being in play are all very much on the map.—

Polls gauging support for the Democrats’ health care bills have revealed increasing discontent. According to the RealClearPolitics average of surveys released from Jan. 3 through Sunday, 51 percent of Americans disapprove of the health care legislation as passed, with 41 percent approving.

In fact, Brown campaigned as a conventional conservative and vowed to be the Republicans’ 41st vote to block health care reform. Central to Coakley’s pitch was the notion that she would preserve the Democrats’ supermajority and the ability to enact a health care overhaul.

But at least some Senate Democrats remain hopeful that health care’s unpopularity and the Massachusetts race will not derail reform when they are so close to sending a bill to Obama’s desk. Sen. Benjamin Cardin (D-Md.) argued that Americans support health care reform generally, and he asserted that their opinion of this bill would improve once it becomes law.

“If you look at the polling numbers, you find that Americans are very much concerned about the current trends in health care. And that the status quo is unacceptable. I think the overwhelming majority of Americans agree with that,— Cardin said. “It’s the uncertainty that causes concern within the polling data. And those that are opposed to the bill, it’s because they don’t — they’ve been told certain things. I think they’re concerned as to whether the bill will deliver as the president has indicated.—

This view is popular among Democrats who have supported health care reform. But Republicans reject it and suggest that those who subscribe to it are condescending to the voters.

Republican operatives maintain that voters across the country — particularly independents — have made a considered judgment about the health care bills and determined that they simply disapprove.

Senate Republicans don’t expect that to change from now to Nov. 2. And based on what they saw in Massachusetts, the GOP is beginning to predict the possibility of much bigger wins on Election Day than they had forecast even one week ago.

“There’s no other way to interpret this,— a second senior Republican Senate aide said.