By WILLIAM DOUGLAS
McClatchy Newspapers

ALLENTOWN, Pa. Sen. Arlen Specter has outlasted many threats to his political survival - the negative publicity he earned from aggressively grilling Anita Hill during Justice Clarence Thomas' 1991 Supreme Court confirmation hearing, close calls in two previous Senate races and two bouts with cancer.

So despite being Pennsylvania's longest-serving senator - he was first elected in 1980 - the 80-year-old lawmaker says he knows only two good ways to run for office: scared or unopposed. Specter freely admits that he's taking the scared approach this year in seeking a sixth six-year term.

"I sure as hell am," said Specter, who switched to become a Democrat last year after decades as a Republican. "It's my nature, never take anything for granted. ... It's a difficult climate for incumbents. ... The voters are madder than hell about the gridlock in Washington. ... There's a lot of concern about the deficit and the national debt."

There's plenty for him to be scared of. His Pennsylvania race is one of the highest profile, most expensive Senate contests in the country. Republicans are angry at him because he bolted their party, and some Democrats, leery of his GOP past, also want to oust him.

"He puts his finger in the air and decides to go where the wind blows," said Tim Gruber, a retired 51-year-old Democratic-leaning independent voter from Allentown. "If it blows towards (former President) George W. Bush, he goes to George W. Bush. If it blows towards Barack Obama, he goes towards Barack Obama. What does he stand for? What's he going to do?"

Sue Wolper, a Democrat from William Township, Pa., said she thinks that Specter has a political compass and she'd vote for him even if he remained a Republican.

"Frankly, I'm pleased that he crossed the line to the Democratic Party," Wolper said after attending a lesbian, gay, bisexual and transgender breakfast meeting with Specter in Allentown. "I'm completely satisfied with him. He takes his constituency seriously."

Specter switched parties a year ago after determining that he couldn't win Pennsylvania's GOP primary.

However, Specter now faces a May 18 Democratic primary against Rep. Joe Sestak, a 58-year-old former three-star Navy admiral whom Democrats were recruiting for the Senate before Specter crossed the aisle.

Sestak, who's represented a suburban Philadelphia district in the House of Representatives since 2006, trails Specter by an average of 14 points in most polls and is considered a long shot.

Still, political observers in the Keystone State haven't written Sestak off yet, largely because his campaign has $5 million in cash and just launched a media ad barrage to raise his name recognition and to portray Specter as a Democrat in name only.

"Pennsylvanians want someone they can trust, maybe not always agree with - who will? - but that they know is there for core beliefs, convictions, not to keep one's job," Sestak said in a recent interview.

Specter has the formidable backing of President Barack Obama, popular but term-limited Pennsylvania Democratic Gov. Ed Rendell, and the major labor unions. Sestak has the support of some liberal Democrats such as Rep. Barney Frank, D-Mass., who called Specter "the same loyal Bush Republican we've seen over the past generation."

If Specter wins the primary, he'd face a tough general election fight against Republican Pat Toomey, a former congressman and one-time head of the conservative Club for Growth.

Specter defeated Toomey in the 2004 GOP primary by only 17,146 votes out of more than 1 million cast. The national Republican Party, still angry about Specter's defection, has vowed to give Toomey anything he needs to defeat the incumbent this time.

"It's glaringly obvious that Arlen Specter is devoid of any sense of principle in his being - you can't trust him," said Brian Walsh, a spokesman for the National Republican Senatorial Campaign. "We are committed to providing any services necessary to win this race. This is one of our top priorities."

Toomey holds modest leads over both Specter and Sestak in polls - anywhere from 6.5 points to 8.8 points. However, few Pennsylvania voters, politicians or political analysts are betting that the senator nicknamed "Snarlin' Arlen" won't pull off another comeback.

"He always seems to be in trouble, but he's a survivor," said G. Terry Madonna, director of the Center for Politics and Public Affairs at Franklin & Marshall College in Lancaster, Pa. "I call him 'The Genie' - he always seems to be escaping out of the bottle. He defies logic in all sorts of ways."

Specter attributes his political longevity to hard work, which he believes generates good luck.

Madonna attributes it to savvy, saying that Specter so far has been able to neutralize Sestak's charge that Specter isn't a true Democrat by voting consistently with the party since he switched.

Specter's voted with liberal Democrats 90 percent of the time since he switched parties, according to the National Journal. As a Republican, Specter split his votes between liberals and conservatives.

At a hearing two weeks ago, Specter even pushed Attorney General Eric Holder to tell Obama to pick a liberal Supreme Court nominee to replace retiring Justice John Paul Stevens and not to worry about a possible Republican filibuster.

"Specter has been brilliant in becoming more of an Obama Democrat than Obama," Madonna said.

While polishing his Democratic credentials, Specter also has been busy raising lots of money. His campaign had raised nearly $13.9 million as of December. Sestak raised $3 million and Toomey about $4.9 million in the same period, according to the Center for Responsive Politics.

The money has helped the campaign shift from meet-and-greets and town hall meetings to an ad war that's likely to get more negative as primary day nears.

Sestak opened with a one-minute spot that focuses on his 31-year naval career, his appointment to President Bill Clinton's National Security Council and his daughter's malignant brain tumor, which sparked Sestak's political interest in health care and spurred him to run for Congress.

Specter put up a 30-second spot called "No Show Joe." It says that Sestak was relieved of duty in the Navy for creating "a poor command climate" and that he missed 127 House votes last year to concentrate on campaigning.

Sestak called Specter's military charge false, and said he was replaced - not relieved - of his Pentagon duty after Adm. Mike Mullen became the head of naval operations in July 2005.

"Admiral Mullen came in and wanted a new team," Sestak said. He accused Specter of employing defamatory "Swift Boat" tactics similar to those used against Democratic presidential nominee John Kerry, a Vietnam veteran, in 2004.

Sestak acknowledges that he missed House votes to tour Pennsylvania's 67 counties in preparation for his Senate run. He said he also missed several votes to attend to his ailing father, who died in September.

Sestak has taken shots at Specter, hammering him over a statement from conservative former Sen. Rick Santorum, R-Pa., that Santorum traded his 2004 endorsement of Specter for Specter's promise that he would support George W. Bush's judicial nominees.

Specter has denied Santorum's claim.

Meanwhile, Toomey waits in the wings.