Today’s vote capped an extraordinarily difficult Washington battle pitting tea party Republican forces in the House against Obama and Democrats controlling the Senate. The resulting compromise paired an essential increase in the government’s borrowing cap with promises of more than $2 trillion of budget cuts over the next decade.

Much of the measure, which the House passed Monday night, was negotiated on terms set by House Speaker John Boehner, including a demand that any increase in the nation’s borrowing cap be matched by spending cuts. But the legislation also meets demands made by Obama, including debt-limit increases large enough to keep the government funded into 2013 and curbs on growth of the Pentagon budget.

“We’ve had to settle for less than we wanted, but what we’ve achieved is in no way insignificant,” said Senate GOP leader Mitch McConnell of Kentucky. “But I think it was the view of those in my party that we’d try to get as much spending cuts as we could from a government we didn’t control. And that’s what we’ve done with this bipartisan agreement.”

Many supporters of the legislation lamented what they saw as flaws and the intense partisanship from which it was forged. In the end, it was a lowest-common-denominators approach that puts off tough decisions on tax increases and cuts to entitlement programs like Medicare.

“What troubles me about it is that the bipartisan compromise also represents a kind of bipartisan agreement by each party to yield to the other party’s most politically and ideologically sensitive priority,” said Joseph Lieberman, I-Conn. “In the case of Democrats, it’s to protect entitlement spending. … In the case of Republicans, it’s to not raise taxes.”

The measure would provide an immediate $400 billion increase in the $14.3 trillion U.S. borrowing cap, with $500 billion more assured this fall. That $900 billion would be matched by cuts to agency budgets over the next 10 years.

The Senate vote was never in doubt after Majority Leader Harry Reid, D-Nev., and McConnell signed on. But like Monday’s House vote, defections came from liberal Democrats unhappy that Obama gave too much ground in the talks, as well as from conservative Republicans who said the measure would barely dent deficits that require the government to borrow more than 40 cents of every dollar it spends.

“This is a time for us to make tough choices as compared to kick the can down the road one more time,” said freshman GOP Sen. Jerry Moran of Kansas.

The measure sets up a fall drama that promises to again test the ability of Obama and Republicans to work cooperatively. It establishes a special bipartisan committee to draft legislation to find up to $1.5 trillion more in deficit cuts for a vote later this year. They’re likely to come from such programs as federal retirement benefits, farm subsidies, Medicare and Medicaid. The savings would be matched by a further increase in the borrowing cap.

There’s no guarantee the committee, to be evenly split between the warring parties, will agree on such legislation. But there are powerful incentives to do so because more budget gridlock would trigger a crippling round of automatic cuts across much of the budget, including Pentagon coffers.

And questions linger about the effect the grueling political free-for-all will have on the U.S. credit rating.

Treasury Secretary Timothy Geithner told ABC News that he didn’t know whether the debt-limit fight would cause America’s AAA credit rating to be downgraded. “It’s not my judgment to make,” he said. Geithner also said he fears world confidence in the United States was damaged by “this spectacle.”

Enactment of the measure provides welcome closure for Obama, who has seen his poll numbers sag during the debt-limit battle.

GOP presidential candidates such as Mitt Romney and Michele Bachmann issued statements opposing the legislation.

“As with any compromise, the outcome is far from satisfying,” Obama conceded in a video his re-election campaign sent to millions of Democrats.

In a tweet, the president was more positive: “The debt agreement makes a significant down payment to reduce the deficit — finding savings in both defense and domestic spending.”