By Susan Heavey and Alistair Bell
WASHINGTON (Reuters) - President Barack Obama is carving out a clear lead in swing states that are key to the November 6 presidential election, even as national polls show him neck-and-neck with Republican rival Mitt Romney.
Helped by the White House's recent loosening of immigration rules, Obama leads Romney in Ohio, Pennsylvania and Florida, according to a Quinnipiac University survey on Wednesday.
An NBC/Wall Street Journal national poll showed Obama ahead of his challenger by just 3 points: a lead of 47 percent to 44 percent which is within the margin of error.
However, the Democrat's lead stretches to 8 points when the race is measured in 12 tightly contested states.
Voters are still deeply worried about the economy, and Obama's campaign could suffer a heavy blow if the Supreme Court rules against his healthcare overhaul on Thursday.
But on paper, Obama seems to have an easier path than Romney to winning 270 electoral college votes, and thus the election, if he can hold on to some of the big swing states he won in 2008.
Among the most contested battleground states today, Obama won Ohio, Pennsylvania and Florida in 2008.
"If he can keep those leads in all three of these key swing states through Election Day he would be virtually assured of re-election," said Peter Brown, assistant director of the Quinnipiac University Polling Institute.
Despite his inroads in key states, voters are still critical of Obama for his handling of the economy.
Forty-nine percent of respondents in the NBC/Wall Street Journal national poll said they are less optimistic about the economy compared with 43 percent who are more optimistic.
Fifty-three percent disapprove of the president's handling of the economy, which is up 1 point from last month.
Although polls consistently show that voters see Romney as less likeable than Obama, the former Massachusetts governor's message that he is a job creator strikes a note with Americans tired of dire monthly unemployment statistics.
Romney "gets a gift from God on the first Friday of every month," analyst Greg Valliere, the chief political strategist at Potomac Research Group, told the Reuters Washington Summit, referring to monthly Labor Department jobs reports. The latest report said unemployment rose a tenth of a point in May to 8.2 percent.
Romney is also looking for an electoral boost if the Supreme Court strikes down all or part of Obama's 2010 healthcare overhaul when it rules on the issue on Thursday.
"My guess is they're not sleeping very well in the White House tonight," Romney said in Sterling, Virginia, a swing state where Obama leads most polls.
"If the court upholds it ... It's still a bad policy and that means if I'm elected we're going to repeal it and replace it," he said at an electronic design and manufacturing company.
SWING STATE BUS TOUR
Obama will likely try to assuage fears about unemployment when he stages his first bus tour of the 2012 campaign in Ohio and Pennsylvania for two days next week.
Obama was ahead of Romney by 9 percentage points in Ohio (47 percent to 38 percent) and 6 points in Pennsylvania (45 percent to 39 percent) in the Quinnipiac poll. He led in Florida by 45 percent to 41 percent.
No one has won the White House since 1960 without taking at least two of those three states.
Respondents in all three states said they favored Obama's order earlier this month to halt deportations of the children of illegal immigrants.
Negative ads targeting Romney as a job killer during his time as a private-equity executive with Bain Capital have helped drag his poll numbers down.
"There isn't a data point that says that the ads aren't working. They're all having an impact," Bill Burton, head of the Priorities USA Action "Super PAC" that backs Obama, told the Reuters Washington Summit.
In the NBC/Wall Street Journal poll, 33 percent of swing state residents - and 28 percent of people nationally - said they had a more negative opinion of Romney based on what they had seen, read or heard about his business record recently.
The swing states were identified as Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, New Mexico, North Carolina, Ohio, Pennsylvania, Virginia, and Wisconsin.
(Additional reporting by Eric Johnson in Chicago, Deborah Charles in Washington and Gabriel Debenedetti in Sterling, Virginia; editing by Mohammad Zargham)