Dick Cheney (search) is only six years older than President Bush, but his long government resume and graying presence helped offset the Texas governor's lack of seasoning and foreign policy experience in 2000.
Those same avuncular qualities seem less politically reinforcing now, with Bush facing a difficult re-election battle and Cheney, 63, burdened by political baggage of his own.
Allegations of profiteering in Iraq by oil services giant Halliburton (search), which Cheney once headed, and his frequent claims that Iraq had weapons of mass destruction have become standard Democratic targets.
Bush strongly backs the former Wyoming congressman, who served as his father's defense secretary and President Gerald Ford's (search) chief of staff. But some Republicans are quietly asking whether Cheney will help or hinder the ticket among voters this November.
That has raised speculation about possible Cheney replacements. Among those mentioned: Senate Majority Leader Bill Frist of Tennessee; Rep. Rob Portman of Ohio; Colorado Gov. Bill Owens; former Pennsylvania Gov. Tom Ridge, now Bush's homeland security secretary; and two New Yorkers: former New York Mayor Rudolph Giuliani and Gov. George Pataki.
"Let's put it this way, I'd love to see Giuliani as vice president," said Jerry Roe, a Michigan historian and former state Republican party executive director. "I think Cheney's health could be a factor. And then add up all the negatives on the Halliburton thing."
Few expect a midcourse ticket correction. Cheney remains popular with the GOP rank and file and with social and economic conservatives who are increasingly uneasy about Bush's deficit spending and immigration-liberalization plans.
But if the president's approval ratings continue to slide, and criticism of Cheney intensifies, it could lead to some GOP soul-searching.
Cheney, who has had four heart attacks, could always step aside on his own, perhaps citing health concerns, analysts suggest. That gives him a potential graceful out -- if he wants one.
Cheney spokesman Kevin Kellems said the vice president's health is "fine," with no recent medical developments that would affect his status. White House spokesman Scott McClellan dismissed the speculation, telling reporters Tuesday that "those rumors are ridiculous."
If not Cheney, who?
Privately, some Republicans suggest a well-established Republican from a populous state, preferably a potential swing state. Wyoming is dependably Republican and offers just three electoral votes.
Portman, actively involved in the Bush-Cheney re-election campaign, said such speculation "is not based on proper analysis of what a vice president brings to the ticket."
"It's not about the three electoral votes that he brings from Wyoming. It's about the sense of stability should something happen. Cheney is viewed as solid ... somebody who could step in if he had to," Portman said. "He's helped by the fact that he says he's not going to run himself. That makes the White House work better."
Cheney has called the vice presidency "my last job."
Not since 1976 has a president seeking another term chosen someone other than his vice president to serve as a running mate. That year, Ford chose Sen. Bob Dole of Kansas after Vice President Nelson Rockefeller decided not to join the ticket. Rockefeller, like Ford, had been appointed to the post. Ford lost his bid.
Loyalty runs deep in the Bush family. Bush's father rejected the advice of some of his most senior aides in 1992 and kept Vice President Dan Quayle on the ticket.
But even his boosters agree that Cheney's role has changed from four years ago. The Sept. 11, 2001, terrorist attacks and wars in Afghanistan and Iraq gave Bush crash experience in international relations.
Cheney also can't help Bush much in the controversies over his National Guard service. Cheney avoided the Vietnam draft with an education deferral.
"This election is going to be about the performance of President Bush," said Curt Steiner, a GOP consultant in Columbus, Ohio. He said the state's battered economy remains a far more important issue than the makeup of the ticket. Bush narrowly won Ohio in 2000.
Jane Earll, of Erie, Pa., a Republican state senator, suggested Bush's choice of Cheney in 2000 over Pennsylvanian Ridge may have contributed to Bush's defeat in the state. "This time around, that's not in play," she said.
Tom Rath, Republican national committeeman from New Hampshire, insisted, "This election is not about the vice presidential candidate."
"I don't think most Missourians are too worried about Halliburton. I think they recognize Cheney for what he is: a very intelligent, soft-spoken guy who carries a pretty big stick," said Hillard Selck, a former Missouri state party chairman.
Some Republican advisers note that, while Cheney's lack of political ambition might be good for Bush, it doesn't help the party groom a candidate for 2008. Of course, similarly, it could leave the door open for a run by Bush brother Jeb, now the governor of Florida.
Van Poole, former Florida GOP chairman and now a Tallahassee lobbyist, doubts that Jeb Bush is considering such a run. And he said Cheney can help Bush in Florida, again expected to be a key battleground.
"Voters see him as a guy with a tremendous amount of experience and who's very smart," Poole said.