Dick Cheney's (search) blistering attack on John Kerry's (search) national security credentials underscores a decision by President Bush's re-election team to give the vice president a more prominent and assertive role in the campaign.

But the strategy also hands Democrats new ammunition, as Cheney's slumping poll numbers and questions about his business ties have cast a cloud over his campaign activities, turning him into a target.

In a foreign policy speech in California on Wednesday, one of several in which campaign aides say Cheney will draw specific contrasts with Kerry on both national security and economic issues, the vice president questioned the Democrat's fitness to be president and challenged his foreign policy credentials.

"The senator from Massachusetts has given us ample doubts about his judgment," Cheney said.

Nicolle Devenish, communications director for the Bush-Cheney campaign, said Cheney would be "putting the meat on the bone" in spelling out of those differences.

"We'll rely very much on his unique ability and his institutional knowledge to make the case for us about important differences," she said.

Cheney's critique was part of a larger administration effort this week to portray Bush as a capable, wartime president and to challenge Kerry's support for the military. It included speeches by top administration officials, a new television ad questioning Kerry's support of U.S. troops and Bush's visit Thursday with soldiers at Fort Campbell, Ky.

Friday is the one-year anniversary of the start of the Iraq war.

Democrats were quick to counterattack.

"Cheney comes out of the bunker: But he's the wrong man to challenge John Kerry on defense," Kerry's campaign said in an e-mailed response that recalled the days after the Sept. 11 terrorist attacks when the vice president was said to be in a "secure, undisclosed location."

Vice presidents often are assigned attack-dog roles to help presidents appear to remain above the political fray. Bush, himself, has challenged Kerry by name, but his jabs have been relatively gentle compared to Cheney's.

Republican strategists hope Cheney's more prominent role will help him deflect recent criticism and re-establish himself after GOP activists began to wonder why he wasn't doing more to help the campaign. That fueled speculation among Democrats — and even some Republicans — that Cheney might be looking for a graceful way to leave the ticket.

But this week's speech appeared as further evidence of Bush's commitment to his running mate, GOP strategists said.

Whether Cheney, famous for his low profile, can be effective, remains dubious, suggested Princeton political scientist Fred Greenstein.

"He's very good for laying out arguments, for framing issues and strategizing. He's a guy who can work board rooms. And he's certainly beloved by the party's base," Greenstein said. "But he's not someone like (Attorney General) John Ashcroft (search) who people can really get indigestion about."

For Cheney, there has been a spate of unwelcome attention:

— A University of Pennsylvania election survey this week put his favorable rating at just 35 percent, down from 60 percent or higher in polls through last June.

— The Pentagon is withholding $300 million in payments to Halliburton (search), the oil-services company Cheney formerly ran, for possible overcharging for meals served to U.S. troops in Iraq and Kuwait. Halliburton and its military services subsidiary, KBR (search), face a criminal investigation into alleged misdeeds.

— Lingering questions about his friendship with Supreme Court Justice Antonin Scalia (search), who refused Thursday to remove himself from a case seeking to force the White House to release documents of Cheney's energy task force. Scalia denied a conflict of interest in taking a hunting trip with Cheney while the court considered the case.

Cheney has even been slammed in some unexpected quarters.

"We're serving the troops because of what we know, not who we know," Halliburton's chief executive, David Lesar, says in a television commercial designed to help the company counter the recent bad publicity and suggestions that it was benefiting because of its association with Cheney.

And, gay Republicans who supported Bush in 2000 are running ads opposing a Bush-backed constitutional ban on gay marriages. The ads by the Log Cabin Republicans (search) show Cheney saying four years ago that, "People should be free to enter into any kind of relationship they want to ... I don't think there should necessarily be a federal policy in this area." The words "We agree" flash on the screen.

But Cheney has said he supports the president's call for an amendment, even though one of his daughters, Mary, is gay.

Republican consultant Scott Reed said Halliburton and other controversies have boosted Cheney's "negatives" in recent polls. "But at the end of the day, Cheney is loved by the base of the Republican Party, both the social conservatives and the economic conservatives."

As to potential swing voters courted by both parties in battleground states, "They're going to vote for the top of the ticket," Reed said.