Mitt Romney’s strong performance in the first presidential debate may have put Pennsylvania back in play, and closed the gap with President Obama in other battleground states.

A Siena Research Institute Poll on Tuesday showed the Republican nominee trailing Mr. Obama by only three percentage points, 43 percent to 40 percent, in the Keystone State. Other polls prior to the debate had shown Mr. Obama with as much as a 12-point lead.

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“Pennsylvania’s 20 electoral votes suddenly appear to be up for grabs,” said poll director Don Levy. “Romney not only has Republican support but now leads in vote-rich areas outside of Philadelphia and also in the central part of the state. With a month and two more debates to go, Pennsylvania’s direction on the road to the White House remains in doubt.”

The Siena survey found 12 percent of the state’s voters undecided. The poll was conducted from Oct. 1 to Oct. 5; the debate took place on Oct. 3.

Meanwhile, the Republican also received a post-debate boost in Wisconsin, where a PPP survey found that Mr. Romney now trails the president by just two percentage points, 49 percent to 47 percent. Two weeks ago Mr. Romney trailed Mr. Obama by seven points there.

In Ohio, an ARG poll taken Oct. 5-8 has Mr. Romney up by one point, 48 percent to 47 percent. Surveys taken there prior to the debate showed the president with as much as an 8-point lead.

In Michigan, an FMW poll taken after the debate showed Mr. Romney trailing by 3 percentage points, just above the margin of error, 49 percent to 46 percent.