Fifty-seven percent of voters believe the U.S. is doing the right thing by fighting the war in Afghanistan now compared to 35 percent who do not, with 8 percent undecided, according to a Quinnipiac University poll conducted Dec. 1-6. That compares to 48 percent who said last month it was the right things to do, with 41 percent disagreeing.

Voters split at 45 percent each on whether they approve of Obama's handling of the war, with 11 percent undecided. That's a marked improvement from last month, when 49 percent disapproved and 38 percent approved.

Obama's decision to send 30,000 more troops to Afghanistan had the backing of 58 percent with 37 percent opposed and 6 percent undecided.

The decision to set a timetable to start bringing troops back home in July, 2011 is supported by a 60 percent to 32 percent margin, with 8 percent undecided. But voters are dubious of whether Obama will meet achieve that goal: 45 percent say he won't, 40 percent say he will and 14 percent are undecided.

Forty-nine percent say they want U.S. soldiers to be in Afghanistan for two years or less, 14 percent are willing to see them stay there two to five years and 31 percent for as long as it takes.

On the Nobel Prize question, 26 percent said they thought Obama deserved to win it and 66 percent did not, with 9 percent undecided.

"President Barack Obama's nationally televised speech explaining his policy and troop buildup has worked, at least in the short term, in bolstering support for the war effort and his decisions," said Quinnipiac's Peter Brown, but he added: "It's probably a good thing for President Obama that the time difference from Norway means the Nobel presentation will occur while most Americans are sleeping and might get less coverage in the United States."