(AP)- Maryland U.S. representatives Donna Edwards and Chris Van Hollen are locked in a divisive battle for the Democratic nomination to succeed retiring Democratic Sen. Barbara Mikulski.
Van Hollen is running as a pragmatic deal-maker. He leads in the polls and in endorsements from prominent Democrats.
Edwards is supported by two former NAACP presidents and the pro-women group Emily's List in her bid to become the first black female senator in 18 years.
Van Hollen, who is white, got a boost from the Obama administration when the White House asked a Super PAC supporting Edwards to withdraw an ad portraying Van Hollen as friendly to the National Rifle Association. The PAC agreed to edit out President Barack Obama's image.
Ten Democrats are on the ballot. Fourteen are vying for the Republican nomination.
Other primary election highlights:
SHEILA DIXON SEEKS RETURN TO BALTIMORE MAYOR'S OFFICE
Former Baltimore Mayor Sheila Dixon is finding strong support for her comeback bid despite her 2010 embezzlement conviction.
She faces a formidable foe in state Sen. Catherine Pugh, the other leading Democratic candidate. The primary winner will likely become Baltimore's 50th mayor, since voters haven't elected a Republican since 1963.
Dixon was mayor from 2007 until she resigned in 2010 following her conviction for using gift cards meant for poor children. She says she'll bring back community policing, expand access to mass transit and build more parks and schools.
Pugh touts her legislative achievements, including her role as Senate majority leader, and her endorsements by many state lawmakers and local black leaders. She says she'll expand neighborhood watch programs and return full control of public schools to the city from the state.
The next mayor succeeds Stephanie Rawlings-Blake, who chose not to seek re-election amid criticism following rioting after the death in custody of Freddie Gray.
BIGGEST MONEY CONGRESSIONAL RACE IN MARYLAND'S 8TH
Money is the most talked-about topic among Democratic contenders for Maryland's 8th Congressional District, which includes suburbs of Washington and Baltimore.
Candidate David Trone has personally put more than $12 million into the contest. That's the most anyone has ever self-funded a House campaign.
Trone owns 150 Total Wine and More stores in 21 states. He entered the race in January, and says he has to spend big to compete with better-known opponents. They include former television news anchor Kathleen Matthews, wife of "Hardball" host Chris Matthews, and state Sen. Jamie Raskin.
All three have liberal social views but Matthews says it's hard to be heard because Trone has controlled the airwaves with his ads.
Raskin says he hopes to show that a grassroots Democrat can beat the big money.
The seat is currently held by Democrat Chris Van Hollen, who is running for U.S. Senate due to Barbara Mikulski's retirement.
Democratic Rep. Donna Edwards is also running for Mikulski's seat, leaving her seat open in the 4th Congressional District. The main Democratic contenders in that heavily Democratic district are former Lt. Gov. Anthony Brown and former Prince George's County State's Attorney Glenn Ivey.
TRUMP, CRUZ AND KASICH ALL MAKE MULTIPLE MARYLAND STOPS
Republican presidential front-runner Donald Trump made two Maryland campaign stops in the week before the primary, attesting to his lead in state polls over Ohio Gov. John Kasich and Texas Sen. Ted Cruz.
Trump's appearances brought large crowds to Berlin Wednesday and Hagerstown Sunday. The New York businessman told the Hagerstown audience that those who vote for him will consider it "the single greatest vote I ever cast."
Kasich visited Rockville Monday. He campaigned April 13 in Savage, near Baltimore.
Cruz campaigned in Frederick on April 21. He appeared in Towson on April 18, eight days before primary election day.
PAPER BALLOTS RETURN; PENS TO BE PROVIDED AT POLLS
Election officials say the return to paper ballots didn't seem to bother voters who turned out during the early voting period April 14-21. About 258,000 people voted early, nearly twice the number who voted early in the 2014 primary, according to the State Board of Elections' website.
Election workers are providing pens to mark the ballots. The system largely replaces touch-screen terminals, which were subject to glitches and security concerns since they were introduced in the state in 2002.
Touch screens haven't entirely disappeared from Maryland polling places. They're built into ballot-marking devices designed for voters whose disabilities prevent them from using the pen-and-oval system. Any voter can choose the touch screens, and a few able-bodied voters will be asked to use them to ensure that votes cast by the disabled can't be singled out.