President Obama leads Republican Mitt Romney in the key battleground state of Ohio, a Fox News poll released Thursday shows.

Obama tops Romney by a six percentage-point margin among Ohio registered voters: 45 percent to 39 percent.  The president’s lead is within the poll’s margin of sampling error.  In February, in the weeks prior to the state’s GOP primary, Buckeye voters backed Romney over Obama by six points (44-38 percent).  

Democrats are slightly more likely to back Obama (83 percent) than Republicans are to back Romney (79 percent).  Independents break for Obama by 39-32 percent.  

Nearly three out of four Tea Party voters support Romney (73 percent), while just over half of voters in union households support Obama (51 percent).  

White working class voters who earn less than $50,000 annually split:  41 percent Romney and 40 percent Obama.

Some 57 percent of Ohio voters are either “extremely” or “very” interested in the November election.  Among those interested voters, Romney tops Obama by 4 points (47-43 percent).  

Click here to view the full results of the poll 

In the 2008 presidential election, Obama’s margin of victory over Republican John McCain in Ohio was less than four percent.  

Ohio Sen. Rob Portman is often mentioned as a potential running-mate for Romney.  Does he give the Republican ticket a boost in his home state?  In a word, no:  An Obama-Biden ticket has six-point edge over a ticket of Romney and Portman (46-40 percent).

While the president’s support is mostly affirmative, Romney’s support is mainly anti-Obama:  63 percent of those backing the Republican say they would be voting “against Obama” rather than “for” Romney (29 percent).  The opposite is true for Obama.  Of those backing the president, 71 percent say they are mainly voting “for” him rather than “against Romney” (22 percent).

For comparison, a recent Fox News national poll found 54 percent of Romney’s supporters are more “against Obama” rather than “for” him (40 percent) (March 2012).  

More voters have a positive opinion of Obama (48 percent) than Romney (36 percent).  Still, the number with an unfavorable opinion each candidate is about the same.  Forty-seven percent have a negative view of Obama, while 46 percent have an unfavorable opinion of Romney.

Despite a spirited Republican primary in Ohio, Romney is still an unknown to some Buckeye voters.  One in six either doesn’t have an opinion the former governor or has never heard of him (17 percent).

A 58-percent majority is pessimistic about the nation’s economy, and by a more than two-to-one margin Ohio voters are more likely to be dissatisfied (68 percent) than satisfied (31 percent) with how things are going in the country today.  

Overall, Ohio voters are split on the job Obama is doing as president:  46 percent approve and 47 percent disapprove of his performance.  Earlier this year 40 percent approved and 49 percent disapproved (February 2012).  The poll was completed before the president’s Wednesday visit to Ohio.

Forty-one percent of voters approve of the job John Kasich is doing as governor, while 43 percent disapprove and 16 percent have no opinion.  That’s up since February, when 37 percent approved and 43 percent disapproved.  

The Fox News poll is conducted under the joint direction of Anderson Robbins Research (D) and Shaw & Company Research (R) from April 15 to April 17, 2012.  The statewide Ohio poll is based on landline and cell phone interviews with 606 randomly-chosen registered voters and has a margin of sampling error of plus or minus 4 percentage points.