RICHMOND, Nov. 2 -- Democratic gubernatorial candidate Timothy M. Kaine won the backing of Richmond Mayor L. Douglas Wilder on Wednesday, an endorsement Kaine hopes will increase turnout among Virginia's black voters in what could be a close election Tuesday.

Wilder, the nation's first black elected governor, said he is supporting Kaine because of Republican candidate Jerry W. Kilgore's position on Virginia's law limiting handgun purchases to one a month.

"I did everything I could as governor to be certain that we did have a change from Virginia being the number one gunrunning state in the nation," said Wilder, who signed the measure into law while he was governor.

"We can't afford to have it even loosened," said Wilder.

Kilgore has said he wants to review the law in light of advances in technology that can speed criminal background checks.

Wilder promised to appear with Kaine and record radio ads for him.

Kaine and Wilder said the endorsement and subsequent campaigning this week could help turn out black voters in Richmond and Hampton Roads, where political observers say Kaine will have to do well in order to win. Polls indicate the race is close.

Wilder is popular among independent voters in general, and political observers and local politicians say he is particularly influential in the state's black communities.

"I think it will help those black voters who are undecided that Tim is the right man," Wilder said in an interview.

The last two Democrats to win the governor's seat have been helped by high turnout among backs. In 1989, when Wilder won, blacks made up 17 percent of the voters, according to an analysis done by the Weldon Cooper Center for Public Service at the University of Virginia. In 2001, when Mark R. Warner took the governor's mansion, blacks constituted 15 percent of the voters. Both Wilder and Warner won 90 percent or more of the black vote. Wilder won his race by a sliver, and Warner won by 5 percentage points.

When George Allen and James S. Gilmore III returned the governor's mansion to the Republicans in the 1990s, black turnout was under 14 percent, according to the center's analysis.

Both Kaine and Kilgore have made last-minute appeals to black voters. Kilgore has run radio ads on black radio stations, as has Kaine this week. Both campaigned at black college homecomings and visited black churches, standard practice in gubernatorial campaigns.

"Yes, I am a Republican, and yes, I am asking for your vote," Kilgore told a Virginia chapter of the NAACP last week. "The fact is, you haven't heard many people in my party stand before you and ask you for your vote. That represents a failure of our democracy and the state of our party."

Kaine has talked up his work as a civil rights attorney and his stint as mayor of Richmond, a city that is 58 percent black. He has also criticized Kilgore, who was then the attorney general, for telling state-supported colleges in 2002 that they could not admit students on the basis of race or ethnic background.

In one ad for Kaine playing on black radio stations, a female voice says: "Kilgore tried to close the door of opportunity for our children. So why should we open the door for him to be governor?"

Black leaders in Hampton Roads and Richmond had expressed concern that Kaine was taking the black vote for granted.

"Six weeks ago, a lot of us were like, 'What's going on?' " said Del. Lionell Spruill Sr. (D-Chesapeake). "We were worried that there wasn't a real plan and that we weren't taking the necessary steps to really energize our voters. Now, it's been like a whole new Tim Kaine."

In a radio ad, Kilgore tried to highlight the concerns expressed by black leaders. The ad says: "Make no mistake, Jerry Kilgore won't take our vote for granted."

Also Wednesday, Kilgore greeted motorists at gasoline stations and told them that Kaine would raise the state gas tax. Kaine has said that he would not support any new taxes until the state guarantees that the transportation trust fund will be used for no purpose other than transportation projects.

Kaine got an endorsement Wednesday from Michael Schiavo, the Florida man who waged a battle to let his brain-injured wife die.

"Even though I am not a Virginian, I care deeply about the outcome of this election because one of the candidates for Virginia governor has said publicly that he would follow [Florida Gov.] Jeb Bush's lead in similar cases," he said in a statement issued by a public relations firm in Florida.

"Every citizen deserves elected leaders who respect individual rights, honor the role of families and follow the rule of law. . . . Mr. Kilgore will not do that, so I implore Virginia voters to elect Tim Kaine governor," he said.

Schiavo was referring to an exchange at an Oct. 9 candidates debate. In that debate, Kaine said that "I don't think governors should use their PR grandstanding to intervene in these cases." Kilgore said that "I'm not going to agree to the forced starvation of any individual if that individual hasn't had a say."

Staff writer Michael D. Shear contributed to this report.

His opponent's views on gun sales won Timothy M. Kaine, right, the backing of Richmond Mayor L. Douglas Wilder.