The final days of the U.S. Senate campaign are looking a lot like the beginning, with the issue of race coloring candidates' campaigns, as Democratic Rep. Ben Cardin and Republican Lt. Gov. Michael Steele scurry to win over African-American voters.

Four days before the general election, Cardin was endorsed by black leaders headed by Rep. Albert Wynn and Prince George's County Executive Jack Johnson. The backing was a counter to support Steele received earlier this week from other leading black Prince George's County Democrats, including former County Executive Wayne Curry.

Meanwhile, Steele on Thursday racked up a few more endorsements of color — a group of black pastors headed by Bishop Harry Jackson, of Hope Christian Church in Lanham.

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At the same time, the Republican Party came under fire for producing a poll-watcher's guide that instructs them to challenge voters' credentials aggressively and threaten elections judges with jail if the challenge is ignored. Thursday's Washington Post reported that critics charged the guide was designed to suppress voting, while analysts said it could lessen black voter turnout.

"They are going to be in Prince George's County aggressively trying to intimidate voters in this county," said Cardin. "We are not going to give up. We are going to make sure that the people in Prince George's County will have the opportunity to get their vote cast and counted."

Cardin said Democrats would not "tolerate these tactics by the Republicans" and called them to withdraw their intention to challenge voters.

Recent polls show the race tight, with Cardin leading Steele, 49 to 43 percent, and 5 percent of voters undecided, according to The Baltimore Sun poll released Thursday. The poll also showed Cardin's backing among black voters has solidified, while Steele has gained from Gov. Robert Ehrlich's performance in certain counties.

Prince George's County, where a third of Maryland's African-American population lives, became the campaign battleground this week. Around 29 percent of Maryland's population is black, according to census database, and they usually make up about 20 percent of Maryland's general election voters.

Race became even more of an issue in Maryland elections after the primary, when most black Democrats lost, including Cardin's opponent former Rep. Kweisi Mfume. Mfume didn't make it to the news conference to endorse Cardin, but was quoted on a flier distributed there.

"I'm proud to support Ben Cardin for Senate," Mfume was quoted as saying.

Johnson, who backed Mfume in the primary, praised Cardin and promised to get out the vote for him, reminding them why they registered as Democrats in the first place.

"This race is not about race," said Johnson. "It's about the fight to re-establish the core values of America, like family, community and access to jobs and educational opportunity. It's about inclusion and how to get this country back on the path of righteousness."

Wynn said the Senate race should not be "trivialized" and the important issue is what the Democrats and Ben Cardin stand for. Wynn mentioned Cardin's vote against the war in Iraq and his work in education and universal health care.

"Up and down the scale you see that Ben Cardin is right on the issues. Ben Cardin is right for our community," he said.

Earlier this week, Curry and five County Council members, endorsed Steele. The decision came from their disappointment with the Democratic ballot without any African-American candidate at the top, and a sense that the county was left behind by the party, they said.

"The party acts as though when they want our opinion they'll give it to us," said Curry. "It will not be like that anymore."

Steele, who became the first black lieutenant governor and lives in Prince George's County, said he was humbled by their endorsement. "I said I did not want this to be so much about party, but about people. And these people understand that."

All the candidates packed their schedules with events as the days before the election dwindle.

Cardin attended a meeting with actor Michael J. Fox Thursday afternoon, then participated in a rally with former Sen. John Edwards, and ended up speaking at a rally with Johnson.

Steele went to Prince George's County to campaign with Curry.

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Capital News Service contributed to this report.