The driver on Benning Road NE cried out to D.C. Council candidate Tom Brown, standing in front of his modest campaign headquarters Sunday: “What you up to?”

“Countdown! Countdown! Countdown!” Brown shouted back.

With hours dwindling before Tuesday’s District primaries, candidates scrambled across the city hunting for votes on foot, in the mail and on wheels. Brown’s Democratic race for the Ward 7 council seat stands to be one of the election’s most competitive, along with the at-large Democratic council race that includes incumbent Vincent B. Orange.

Brown is one of four candidates trying to unseat five-year member Yvette M. Alexander, and he has seen a surge of support in recent weeks, picking up major endorsements from newspapers, labor and business groups.

He tried to solidify his support Sunday by knocking on doors after attending three Palm Sunday church services and doing a radio interview. Alexander attended Sunday Mass at her home parish, Holy Redeemer in Ward 6, and spent time with friends and family a day after organizing a motorcade of more than a dozen vehicles through her home ward’s streets.

Palm Sunday, she said, was a “friends and family day,” light on campaigning. “Tomorrow is another day,” she said. “We haven’t wrapped it up. We’re still going hard.”

Also running are Kevin B. Chavous, a Hillcrest lawyer and son of a former council member; William Bennett II, a Deanwood minister; and Dorothy Douglas, a Deanwood activist and school board member. A small group of 1,400 registered Republicans in the ward will also vote in a rare contested GOP primary, between activist Ron Moten and businessman Don Folden Sr.

In an election in which most observers expect that fewer than 50,000 will vote, 6,051 voters had already cast ballots at early voting locations that closed after Saturday’s balloting.

A tough race has emerged in Ward 8, where former mayor Marion Barry is facing hard-charging Democratic challengers in his campaign for a third consecutive council term. Races in other wards are less competitive, with incumbents Jack Evans of Ward 2 and Muriel Bowser of Ward 4 expected to win their Democratic primaries handily.

Voters will also choose party nominees for president, although no surprises are expected: President Obama is running unopposed in the Democratic primary, and on the GOP side, former Massachusetts governor Mitt Romney is heavily favored to secure the 16 delegates up for grabs. Romney’s chief rival, Rick Santorum, the former U.S. senator from Pennsylvania, did not attempt to qualify for the ballot in the District.

The final hours of the Democratic at-large contest have turned into a grudge match between the incumbent and Sekou Biddle, who briefly filled the seat last year before losing to Orange in an April special election.

Former Prince George’s County Council member Peter Shapiro and Ward 1 Advisory Neighborhood Commissioner E. Gail Anderson Holness are also vying for the seat, and the expected low turnout has kept the citywide race fluid.

On Saturday, Shapiro and his wife, Julia Wright, took on the grueling task of weeding out potential voters at Eastern Market, a hub for the District’s transient population.

Orange is expected to rack up large margins in his home base of Ward 5 and east of the Anacostia River. With Biddle and Shapiro both competing heavily for votes in more affluent neighborhoods, there is considerable risk that they could split the anti-Orange vote.

In an indication that turnout could be highest in the city’s western end, statistics released by the D.C. Board of Elections and Ethics show that more than a quarter of the early votes were cast at a polling place in Ward 3, amid the city’s most affluent neighborhoods in upper Northwest, followed by a downtown voting location.

Orange vows he’s also pushing for votes in Northwest, as evidenced by a campaign stop he made Saturday in Georgetown. Wearing a button that read, “Vote for the Double O, Obama & Orange,” the council member won over Chris Lapetina near 31st and O streets NW.

“The fact you are here shows you are willing to listen to people’s concerns,” said Lapetina, who is worried about city tax rates.

In North Portal Estates, however, Biddle appeared to be making inroads in a neighborhood that both he and Orange see as vital to their chances. Marva Benjamin said she worries about “the people around Orange.”

“It has to do with me thinking about his priorities,” Benjamin said. “When I’ve seen him, I haven’t been impressed.”

As with most D.C. elections, a big unknown remains — which campaign will have the most effective operation to try to drive up turnout in its favor. Shapiro said he has decided against a second mailer in order to put as many as 300 staffers and volunteers on the streets Tuesday. Orange, who has been endorsed by most local labor organizations, said he will be focusing his resources on key precincts with the help of “union support.”

Biddle, who is not devoting paid staff to a vigorous get-out-the-vote push, said he’s confident in his strategy for what is expected to be a low-turnout election. “The reality is, in a race like this, the people who are coming out to vote are the people coming out to vote,” he said.