WASHINGTON - Two early showdowns on spending and debt will signal whether the new Congress can find common ground despite its partisan divisions or whether it's destined for gridlock and brinkmanship that could threaten the nation's economic health.

Not all of the bickering in the 112th Congress that convenes Wednesday will be between Republicans and Democrats. House Republicans, back in power after four years in the minority, will include numerous freshmen whose unyielding stands on the deficit, in particular, could severely test soon-to-be Speaker John Boehner's ability to bridge differences and pass major bills.

His first big challenge will come in February, when Congress must pass a huge spending bill to keep the government running. Many House Republicans - veterans and newcomers alike - have pledged to cut discretionary domestic spending by up to $100 billion.

Even if they agree on a plan, it probably will be changed by the Senate, where Democrats will hold a 53-47 edge. And President Barack Obama can veto almost any bill he opposes during the next two years.

Before Boehner, R-Ohio, deals with Democrats' objections, he may have trouble getting his own 241-member caucus to agree on what to cut, and how deeply. Republicans have a history of promising far more cuts in spending than they deliver. Some conservative activists and commentators are tired of it.

"They love to cut taxes but cannot bring themselves to cut spending," Kevin Williamson wrote in National Review Online. "It's eat dessert first and leave the spinach on the table."

Several freshman GOP lawmakers are aligned with the tea party movement, which champions spending cuts and balanced budgets. But even tea party activists are unable or unwilling to name sizable government programs they are willing to cut, said Duke University political scientist Mike Munger. He ran for North Carolina governor as a libertarian and has met with many tea partyers.

Passing a major spending bill may look easy when compared with the challenge Congress will face in the spring: raising the federal debt ceiling, an exercise that's anathema to some die-hard conservatives. Economists and scores of political leaders say the alternatives are much worse: Let the nation default on its debts, which could trigger a global recession, or drastically cut federal spending to levels neither party has imagined.

The current debt ceiling is $14.3 trillion, enacted last February. The federal debt, nearly $13.9 trillion, grows by $4 billion a day.

"Where the rubber will hit the road will be on the debt limit," said John Feehery, a Republican adviser and former top House aide. "What kind of budget concessions will Obama agree to in exchange for keeping the government functioning?"

Lawmakers might buy some time by passing temporary extensions of a budget and a higher debt ceiling. Eventually they must work out a long-term solution. Obama has made it clear that Republicans share responsibility for finding one.

"Nobody, Democrat or Republican, is willing to see the full faith and credit of the United States government collapse," Obama said in early December. No one enjoys voting to raise the debt limit, he said. "But once John Boehner is sworn in as speaker, then he's going to have responsibilities to govern. You can't just stand on the sidelines and be a bomb thrower."

Boehner essentially has acknowledged that. He said of the debt ceiling, "We are going to have to deal with it as adults, whether we like it or not. The federal government has obligations and we have obligations on our part."

Lawmakers say the likeliest scenario calls for a promise of future spending cuts, even if somewhat vague, that might persuade enough House Republicans to agree to raise the debt ceiling.

Some predict a fierce fight. The national Republican Party chairman, Michael Steele, seemed to encourage lawmakers to vote against a higher debt ceiling shortly before the November elections. "We are not going to compromise on raising the debt ceiling," he told CNN.

If Congress fails to reach accord on either a spending bill in February or a debt ceiling solution, it's possible that much of the federal government would shut down for lack of funding. That's what happened in 1995, and many Republicans don't want a repeat.

The GOP-led Congress at the time clashed with President Bill Clinton over the budget, letting portions of the government close during the impasse. Public opinion swung against the Republicans, and the episode helped propel Clinton toward his 1996 re-election.

Even if the Boehner-led House can resolve its budget and debt differences with the White House, there could be trouble in the Senate. Republicans there can halt almost any bill with a filibuster.

Republican Sen. Bob Corker of Tennessee hopes to lead a group of colleagues in demanding tax and spending reforms before they agree to raise the debt ceiling.

But eyes will fall first on the House. Sixty-four Democratic-held seats have switched to Republicans, and some of the new GOP lawmakers have promised voters they would change the way Congress spends itself into debt.

"I don't envy John Boehner," said David DiMartino, a Democratic consultant and former Senate aide. "The looming vote on the debt ceiling will demonstrate Boehner's ability to lead," he said. "If that vote melts down he's likely to fail to regain any semblance of control."

The White House is offering little sympathy.

"There are no easy choices when it comes to cutting spending," said White House communications director Dan Pfeiffer. Republicans ran a successful campaign by promising vaguely to cut taxes and spending, he said, and now they have to present a budget and "explain what it is they are willing to cut."