Amid spiking disillusionment with the political process, Americans are split on whether to blame President Obama or Republicans for the S&P credit downgrade or Washington’s generally out-of-touch behavior, according to a new Washington Post poll.

Obama’s political standing is weaker in the aftermath of the fierce debt negotiations, especially among liberals. There’s also stronger opposition than support for a second term among swing voting groups who backed him in 2008, including independents and women.

More than four in 10 Americans say they "definitely will not" support Obama in 2012, while fewer than half as many, just two in 10, are certain to back the president for reelection. The number of “definite” Obama voters marks a low in polls since November 2009 and has dropped four percentage points since a Post-ABC poll in June, and eight points since April.

Support for Obama has softened considerably on the left: In the new poll, 31 percent of liberals say they are certain to vote for Obama next year, down from 46 percent in June. One in five liberals says they “definitely will not” vote for him, while a 43 percent plurality says they’ll considering casting a ballot for Obama.

Obama’s 2008 election was fueled by winning majorities of key swing groups, including political independents, women and voters under age 50. But with 15 months left before Election Day, more than three times as many independents say they “definitely will not” vote for Obama in 2012 as say they “definitely will” — 45 percent versus 14 percent. And among women and those under 50, more say they’ll definitely oppose than definitely support Obama next year.

Lack of enthusiasm about awarding Obama a second term hasn’t translated into support for the current GOP nominees among swing voting groups. Asked in a mid-July Post-ABC poll how they would vote if the election were held today, political independents, moderates, women and adults under age 50 chose Obama over Mitt Romney, Rick Perry (R-Texas) and Michele Bachmann (R-Minn.), three top contenders for the Republican nomination. The margins are closer among registered voters, but even then only Romney pulls even with Obama among independents, 47 percent to Obama’s 48 percent.

Read the full poll results .

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