WASHINGTON — Democratic Sen. Joe Manchin might leave Washington early for West Virginia and run for governor, rather than suffer through another four years of a Senate riven by political hostility.

So far, though, the word he wants to hear — bipartisanship — is on everyone's lips. Manchin and his coal state interests have found a more receptive audience in the Republican-led Senate, and he's challenging President Barack Obama over construction of the Keystone XL pipeline. He also stands to wield more clout as a centrist Democrat who might be helpful during tough votes the GOP can't win alone.

But the new Congress is only a few days old. The professed bipartisan spirit is fragile. And Manchin is keeping his options open.

"I'll make a decision by this summer, end of the spring," the 67-year-old senator and former governor said in an interview with The Associated Press. He refused to commit to serving out his Senate term, which runs through 2018.

"I didn't come here to sit on my hands. The last four years are the most unproductive years of my working life," Manchin added. "I'd like to think basically I'm involved in this great body, that I can contribute from my state of West Virginia and make sure (my constituents) are heard."

His indecision highlights the cost and legacy of congressional dysfunction that brought lawmaking to a near-halt in recent years and caused several retirements out of sheer frustration. Sen. Olympia Snowe, the Maine Republican centrist who retired in 2012, spoke for many leaving the chamber in the rearview that year when she cited "dysfunction and political paralysis" as the reason.

Manchin knows the Senate no other way. The former West Virginia governor — he served from 2005-10 — took office in a special election in 2010 when Robert C. Byrd died after 51 years in the Senate. Democrats remained in charge, but across the Capitol, a tea party-driven electoral wave flipped control of the House to Republicans. The divided Congress embarked on a four-year streak of partisan standoffs that brought the nation to the brink of economic collapse and made compromise a political loser for many lawmakers.

For Manchin, conservative West Virginia's only Democrat in Congress, centrism and opposing the White House are political survival tools. Republicans hit him in the 2010 election as a rubber stamp for Obama. Manchin fired back with an ad in which he used a rifle to shoot a bullet through an alleged copy of the Democrats' carbon emissions bill. He won his seat in the Senate with 53 percent of the vote that year. In 2012, Manchin won re-election with 61 percent — while Obama lost every one of West Virginia's 55 counties against Republican rival Mitt Romney.

In 2013, after the shooting deaths of schoolchildren and their educators in Newtown, Connecticut, Manchin joined Republican Sens. Mark Kirk of Illinois and Pat Toomey of Pennsylvania on a bill to expand background checks on some gun purchases. The measure fell to a Republican filibuster and entangled Manchin in an ugly squabble with a key supporter, the National Rifle Association.

Then came Election Day 2014, when voters handed Republicans control of the Senate — and gave Manchin the prospect of more sway as a centrist sought after by Republicans.

Senate math tells the story: Republicans gained nine seats for a total of 54, a majority of the 100-seat chamber. But the rules say 60 votes are required to overcome filibusters — objections that can halt legislation — meaning Republicans now need six Democrats to join them to reach that threshold and advance controversial measures.

With the new Congress only a few hours old Tuesday, the White House announced that Obama would veto the Keystone bill. Manchin heard about it from an aide who read aloud from a news clip on his mobile phone.

"Oh, hell, I didn't think it could get any worse," Manchin fumed to reporters.

On Thursday, he was the lone Democrat on the Energy and Commerce Committee to vote to advance the Keystone bill.

In fact, feuding with Obama could be helpful for a Democrat from a state rushing rightward.

"My guess is he wouldn't be doing it if it weren't," said Sen. Jon Tester, D-Mont.

Manchin vowed to forge ahead with the bill in a committee session Thursday.

After all, Majority Leader Mitch McConnell, R-Ky., eager to show Republicans can govern in the run-up to the 2016 presidential contest, is promising progress, if not specifics. Democrats will be allowed to offer amendments to Republican bills, McConnell has said.

And in private?

"He just basically says, 'I think you're going to like this process,' " Manchin recalls.