Conservatives are urging John McCain to go for the jugular in the final presidential debate Wednesday night and attack Barack Obama for his relationship with the Rev. Jeremiah Wright.

"The Jeremiah Wright issue is a perfectly legitimate issue," syndicated columnist Charles Krauthammer told FOX News. "Jeremiah Wright is not a casual acquaintance. He's a guy that Obama has told us about in his books. He was a very important influence on his adult life, probably the most important influence on him after his wife. And we know what kind of man Wright is and what he believes."

Wright, a fiery pastor who established one of the most powerful churches in Chicago until his retirement earlier this year, is credited by Obama for bringing him back to his Christian roots. But the Democratic candidate left Trinity United Church of Christ after 20 years in the spring after videotapes surfaced showing Wright's angry and provocative criticism of America's foreign policy and its history of oppressing minorities.

McCain and running mate Sarah Palin have gone after Obama in recent weeks for his association with former domestic terrorist William Ayers, accusing Obama of lying about their true relationship in ads and at rallies. McCain has softened that attack on the campaign trail in recent days, though not in his TV and radio ads.

Obama and McCain plan to lay out their vision for the country and promote their economic policies in Wednesday night's debate, which will air at 9 p.m. ET on all major broadcast and cable news networks. But McCain, who is trailing in the national polls as well as in most of the critical swing states, is expected to unleash character attacks on his opponent after both Obama and running mate Joe Biden challenged him to "say it to my face."

McCain's top advisers and Palin believe he should attack Obama over Wright. But McCain is said to fear being painted as a racist if he does.

"It's a completely unfounded charge," Krauthammer said, "but McCain has flinched."

Democratic strategist Paul Maslin said it's "ludicrous" for conservatives to push McCain to attack Obama on his relationship with Wright.

"We've had a virtual meltdown of our economy and they think he's going to make up ground in the polls by going after Jeremiah Wright or Bill Ayers," Maslin said. "It's preposterous."

Conservative commentator Tucker Carlson said he envisions a McCain ad featuring Wright's most inflammatory statements: 

"God damn America for treating our citizens as less than human. God damn America for as long as she acts like she is God and she is supreme," Wright railed in one of his sermons.

"We bombed Hiroshima, we bombed Nagasaki, and we nuked far more than the thousands in New York and the Pentagon, and we never batted an eye. ... America's chickens are coming home to roost," Wright once said.

Carlson said the narrator in his imaginary ad would then state, "For 20 years, Barack Obama sat in the pews, even brought his family, as Wright preached hate. Obama never said a word, until he was caught. Then he defended Wright. Barack Obama: Divisive. Dishonest. Dangerous."

Three conservative Californians also have created an ad featuring Wright that declares, "Barack Obama seems to have different values from most Americans." It's unknown, though, how widely the ad, which is not approved by the McCain campaign, will air. 

Maslin said he doesn't believe McCain will raise Wright at all, adding that such an attack would backfire and put more Republican congressional seats in jeopardy in next month's election.

"John McCain at some point has to realize his legacy is at stake here," Maslin said. He said McCain would return to the Senate humiliated if he tried to mollify the right wing of the party with the character attacks.

FOX News' Stephen Clark contributed to this report.