Former president Bill Clinton, preaching before one of Prince George's County's largest congregations, yesterday delivered a rousing call for black voters to turn out on Election Day for Democratic candidates.

Clinton took to the pulpit at Jericho City of Praise Church in Landover and gave a throaty sermon on behalf of Kathleen Kennedy Townsend, the party's candidate for governor, and Christopher Van Hollen Jr., who is trying to unseat Rep. Constance A. Morella in Maryland's 8th District.

"If half of you stay home, we'll be out of business on Wednesday morning, and so will you. You'll pay the price, not the politicians. Don't worry about us. We'll be just fine, thank you very much," Clinton said.

"Now are you going to show up?" he asked, and the crowd of 5,000 roared in approval.

"Are you going to blow down the walls of oppression? Are you going to build up the opportunities for your children? You better be there."

The audience of mostly African American parishioners, packed into the pews, cheered as the choir sang, "The Best Is Yet to Come."

"It was absolutely right on," said Mynaca Ojo, 40, of Gaithersburg. "These people vote, and they know people who vote."

Those votes are crucial to both campaigns, which are locked in statistical dead heats, according to the most recent polls. That has made turnout the focus of campaign efforts for Democrats, who outnumber Republicans by more than 2 to 1 on Maryland's voter rolls.

Republican Robert L. Ehrlich Jr. yesterday predicted he would overcome that margin and become the the first Republican governor in Maryland since Spiro T. Agnew.

"We feel it. It's called a big victory," he told a cheering crowd of about 80 enthusiastic seniors at Leisure World in Silver Spring. "It's not going to be that close," he added.

Ehrlich also spoke confidently during an hour-long interview on WTOP radio and criticized his opponent for declining an invitation from moderator Mark Plotkin to join him.

"It was supposed to be a debate," Ehrlich said. "The lieutenant governor yet again would not show up."

Townsend spent her morning at events in suburban Baltimore before heading to Prince George's for a fundraiser and rally with Clinton.

The former president's persuasive pitch to African Americans four years ago was widely credited with delivering the election to Gov. Parris N. Glendening (D), who had been in a tight race with his Republican opponent, Ellen R. Sauerbrey, until the campaign's final days.

Peter Hamm, a Townsend campaign aide, said that the lesson from 1998 is resonating this year and that he believes the final weekend of the campaign will be devoted to "a thunderous appeal to Democratic base voters."

"We're telling them that nothing matters more than getting out to vote on Tuesday," Hamm said.

The state Democratic Party has spent months fine-tuning a fiercely aggressive Election Day plan, which employs unions, churches and other loyalists to cajole, nudge or even drive voters to the polls.

For Van Hollen, the push has meant overcoming his poor showing in the 10 Prince George's precincts against his opponent in the primary, Mark K. Shriver. Since then, Van Hollen has opened an office there, and he is delivering a recorded phone message from Clinton to the most heavily African American and Latino neighborhoods. Today, he and Shriver will join in a caravan tour through the area.

Appealing to African American voters has also been on the agenda of Maryland's Republican candidates. Ehrlich started airing a series of ads this week aimed primarily at black voters. One features a black Baltimore police officer, another Ehrlich's running mate, Michael S. Steele, who is African American.

Ehrlich and Steele appeared Thursday in Prince George's, pledging to adopt a faith-based initiative that could allow churches to work more closely with state government. Ehrlich is returning today to meet with voters in Cheverly and tomorrow for church services.

Morella has attended several services at black churches, and yesterday she campaigned in Mount Rainier, a heavily black area, and walked through business districts. One of her brochures talks about the minority issues she has worked on, such as winning funding for a memorial to the Rev. Martin Luther King Jr. in Washington. And, like Van Hollen, she is running ads on black and Latino radio stations.

"National Republicans told us not to spend money on that kind of thing, but she doesn't care," said campaign manager Tony Caligiuri. "She feels it's important to show she is reaching out to every voter."

For Democrats, Clinton has been playing the part of ambassador to the black community. Yesterday was his second appearance in Maryland for Townsend. His previous visit, two weeks ago, involved a boisterous rally at Coppin State College followed by three fundraisers.

Last night, Clinton tucked in a quick joint fundraiser for the two Democrats in a drab conference room at the Landover Doubletree Hotel, off the Capital Beltway.

About 50 guests paid as much as $4,000 to stand in line to pose for a snapshot with Clinton, Townsend and Van Hollen against a blue felt curtain.

Campaigning in Lanham are Clinton; Kathleen Kennedy Townsend; her running mate, Charles R. Larson, left; and Christopher Van Hollen Jr., right.