Two candidates, both former Democrats, are looking to block Rep. Albert R. Wynn (D-Md.) from returning to Capitol Hill for a seventh term.
Although neither of the challengers, John McKinnis and Theresa Mitchell Dudley, has held elected office, Wynn said he was campaigning hard in the 4th District.
"In politics, you can never take anything for granted," Wynn said recently.
Prince George's voters also will elect a U.S. senator and members of the House of Representatives from either the 5th or 8th districts Tuesday. In addition, they will consider a ballot issue that would add two at-large seats to the County Council.
McKinnis, a Silver Spring resident, owns an information technology firm in Beltsville. Dudley is a public school teacher and community activist in Landover.
McKinnis said he switched to the GOP six years ago because the Democrats had moved too far to the left. Dudley, who has run three times for County Council as a Democrat, turned to the Green Party to challenge Wynn.
Both have criticized him for pushing to bring a casino resort to Prince George's County and for what they see as a heavy hand in local matters.
"I figured if I have to run against Al Wynn every time I run for council, I might as well run against him," Dudley said.
" 'I got you elected, you gotta do it my way,' " McKinnis said of Wynn's relationship with council members and the county's delegation to Annapolis.
Wynn says he is serving his constituents.
In the 5th District, Republican Brad Jewitt, 34, the former mayor of Berwyn Heights, faces 12-term incumbent Democrat and House Minority Whip Steny H. Hoyer.
Jewitt, a member of the U.S. Marine Corps Reserve, said that Hoyer is more liberal than his constituents, citing Hoyer's opposition to a ban on late-term abortions and his vote against constitutional amendments to prohibit same-sex marriage and flag burning.
"My opponent doesn't share our views and values," Jewitt said.
Hoyer's supporters praise the millions in federal dollars he has steered to the district, much of it to Patuxent River Naval Air Station and Indian Head Naval Surface Warfare Center.
Hoyer, 65, of Mechanicsville, said the deficit is the most urgent problem facing the country. He called President Bush's tax cuts of 2001 and 2003 "fiscally irresponsible."
Jewitt supports further tax cuts, although he declined to say how Congress could implement them without increasing the national debt.
In the 8th District, Rep. Chris Van Hollen (D), who survived a bruising campaign in 2002 to defeat a 16-year Republican incumbent, finds himself facing a pesky GOP challenger.
Chuck Floyd, who moved to the district 18 months ago, has spent more than $200,000 of his own money to oust Van Hollen.
A retired military officer and State Department employee who lives in Kensington, Floyd said that Van Hollen is too liberal and partisan to be effective in the Republican-controlled House." With my background and experience, I'll get more done in 90 days than my opponent has done in two years," Floyd said.
Van Hollen, supported by a coalition of labor, environmental and gun control organizations, scoffed at the suggestion that he is a backbencher.
"One thing my constituents want is someone who is a strong voice on the issues they care about, not someone who is always hedging their bets," he said.
In July, Van Hollen joined with Republican Jeff Flake (Ariz.) to lead passage of an amendment prohibiting the use of federal funds for a $10 billion buyout of tobacco farmers. A House-Senate conference committee then agreed to make the tobacco companies pay for the buyouts.
A member of the Education and Workforce and Government Reform committees, Van Hollen also points to his efforts to increase funding for special education.
Van Hollen opposed Bush's decision to invade Iraq. He said he believes his views will resonate with voters in a district where Democrats outnumber Republicans 2 to 1.
Floyd, who supports the war, says Van Hollen is beholden to the liberal wing of the party.
"I need to talk about his records," Floyd said in a recent debate. "He's voted 99 percent of the time with his own party."
In the Senate race, incumbent Barbara A. Mikulski (D), who has held the seat since 1987, is facing an energetic challenge from state Sen. E.J. Pipkin (R-Queen Anne's), a former Wall Street junk bond dealer who has used more than $1 million of his own money to finance his race.
A native of Dundalk, Pipkin returned to Maryland in the late 1990s. He was elected to the state Senate in 2002 after helping lead a fight against dumping the spoils dredged from Baltimore's harbor into the Chesapeake Bay.
His campaign has focused on what he says is Mikulski's pattern of supporting higher taxes, opposing defense spending and sending soldiers to war without proper equipment or pay.
Mikulski, who is from East Baltimore, said Pipkin is distorting her record. She serves on the Senate Appropriations Committee and has pursued legislation that she says is aimed at helping the elderly, middle-class families and college students trying to pay rising tuition costs.
Her campaign has raised more than $5 million. Coupled with Pipkin's substantial self-financing of his campaign, the race has become one of the most expensive in Maryland history.
Voters in Prince George's will also decide whether to add two at-large seats to the County Council and if the voters -- not council members -- should select the council's chairman.
Question H was placed on the ballot after the Association of Community Organizations for Reform Now collected more than 11,000 signatures. The grass-roots organization said an expansion of the council would give the community a greater voice in countywide issues.
Opponents, including the majority of the County Council, have added questions to the ballot that would block council member Thomas R. Hendershot (D-New Carrollton) from running for an at-large seat; retain the council's power to elect the chairman; and prohibit at-large members from being able to vote.