By Joseph Ax

PHILADELPHIA (Reuters) - As he seeks re-election to his U.S. Senate seat this November, Pennsylvania's Pat Toomey can make an unusual claim. He is the sole Republican nationwide running with the endorsement of top U.S. gun control advocates Gabby Giffords and Michael Bloomberg.

That pair of endorsements could give the first-term senator an edge over Democratic challenger Katie McGinty, a former environmental official in the White House and the Pennsylvania governor's office. The race is one of a handful of close contests on Nov. 8 that could determine whether Republicans, currently with a 54-46 majority, maintain control of the Senate.

Both candidates are targeting educated moderate voters, particularly in the Philadelphia suburbs, many of whom may be turned off by the rhetoric of Republican presidential candidate Donald Trump, according to political analysts in Pennsylvania.

McGinty, who calls her support of gun control measures stronger than Toomey's, is working hard to dismiss his endorsements from Giffords and Bloomberg, and has touted her own endorsement by a Pennsylvania anti-gun violence group.

Giffords, considered a hero by many gun control advocates, is a Democratic former U.S. congresswoman from Arizona who survived being shot in a 2011 assassination attempt and has become an activist for gun restrictions. Bloomberg is the billionaire former New York City mayor who considered a run for the presidency this year and, since leaving office, has focused much of his energy on gun control.

McGinty has called Toomey's commitment to gun safety "paper thin" and notes that the Republican incumbent received an "A" rating from the influential National Rifle Association gun rights lobbying group during his first Senate run in 2010.

The issue of gun rights is potent in a nation where the right to "keep and bear arms" is enshrined in Constitution's Second Amendment. The NRA opposes candidates who support gun control efforts including restricting the types of firearms people can own or expanding background checks required for gun buyers. Many Republicans side with the NRA, while many Democrats support gun control.

Opinion polls show Toomey's race as virtually tied, even as Democratic presidential nominee Hillary Clinton leads Trump by several percentage points in a state that has voted Democratic in the past six presidential contests, starting in 1992.

Pennsylvania is home both to rural communities where hunting is a popular pastime and big cities including Philadelphia and Pittsburgh where crime and gun violence are major concerns. Shifting attitudes on guns in the state have emboldened both parties in Pennsylvania to distance themselves from the NRA's stance opposing almost any effort to restrict gun rights.

The state's law mandating background checks for private handgun sales already goes beyond federal law, said Terry Madonna, director of the Franklin & Marshall College Poll in Lancaster, Pennsylvania.

"Pennsylvania has a very substantial hunting and fishing culture," Madonna said. "But hunters aren't opposed to that."


Toomey's position on guns sets him apart from most of his Republican U.S. Senate counterparts, as he tries to attract moderates while keeping conservative voters in his column.

In a telephone interview, Toomey said the Giffords and Bloomberg endorsements recognized "that what I did was a very hard thing to do politically." He also emphasized his belief that most gun owners share his position.

"I'm a strong Second Amendment supporter," Toomey said. "I see no contradiction between that support and insisting on background checks, so that people who've got no right to the Second Amendment because they're dangerous criminals or they're dangerously mentally ill or they're terrorists, should be denied a firearm any way we can."

Giffords has also endorsed Illinois Senator Mark Kirk, another Republican running for re-election, though Bloomberg has not weighed in on that race.

In an email, McGinty told Reuters Toomey is "no moderate" when it comes to gun violence.

"Time and again, he has sided with the gun lobby instead of doing what's right to keep communities safe," McGinty said. "Pat Toomey has completely run away from legislation to expand background checks, since it failed to pass the Senate three years ago."

Toomey made headlines in 2013 following an elementary school massacre in Newtown, Connecticut, when he and Democratic Senator Joe Manchin of West Virginia introduced legislation to expand background checks for gun buyers nationwide.

That legislation, fiercely opposed by the NRA, failed in the Senate, but Toomey gained praise from Democrats for bucking the majority of his party.

He voted for a similar bill after the mass shooting last year in San Bernardino, California, and supported Republican-backed legislation in Congress this year following the Orlando nightclub shooting to restrict access to firearms for people on official "terrorism watch lists."

McGinty backed a stricter Democratic-backed version. None of the measures passed.

McGinty, who called Toomey's gun control positions weak, favors more sweeping restrictions such as bans on military-style "assault weapons" and high-capacity ammunition clips that Toomey opposes.

In a recent television ad, McGinty used a clip of Toomey telling voters this summer that he had a "perfect record" with the NRA. The NRA has not yet released ratings or issued an endorsement in the race.

Toomey called McGinty a "political opportunist" and again pointed to his support from Giffords and Bloomberg.

"The idea that somehow they've all got it wrong and Katie McGinty, my opponent, has it right is just laughable," he said.

(This story corrects Senator Mark Kirk's home state to Illinois from Ohio in 15th paragraph.)

(Reporting by Joseph Ax; Editing by Scott Malone and Will Dunham)