Wearing white Chuck Taylor sneakers with her gray pantsuit, Angela Alsobrooks was in the middle of a whirlwind day of campaigning in the vote-rich suburbs of Maryland last week when a voter confronted her with the question on everyone’s mind: Was she the candidate with the best chance of keeping the state’s up-for-grabs seat in the United States Senate in Democratic hands?
It’s an unfamiliar question for deep-blue Maryland, which hasn’t had a Republican senator in nearly four decades. But the state’s typically sleepy Senate race has heated up this year after Larry Hogan, the popular former two-term Republican governor, decided to run.
Now Democrats across the state are wringing their hands trying to figure out which of their candidates has a better shot at defeating Mr. Hogan. The primary, which is set for Tuesday, pits Ms. Alsobrooks, the Prince George’s County executive who is trying to become the first Black person and second woman from Maryland to serve in the Senate, against Representative David Trone, a wealthy third-term congressman who is smashing self-financing records — he has spent more than $61 million of his own money, flooding the airwaves with TV ads — to secure a victory.
Perhaps because of the heightened stakes, the contest has turned increasingly negative as it has tightened, splitting Democrats in Congress and beyond. While congressional leaders have endorsed Mr. Trone, all but one Democrat in the state’s congressional delegation are backing Ms. Alsobrooks. She also drew support from several Black lawmakers from other states after Mr. Trone used a racial slur at a congressional hearing — a remark for which he later apologized, saying he meant to say a different word.
Barbara Peart, 76, the voter who questioned Ms. Alsobrooks last week about her chances, said she did so because she was terrified that a Republican could win the seat and flip the Senate, boosting the agenda of former President Donald J. Trump.
“It’s scary because it’s no exaggeration that it’s the most important race in a long time,” Mrs. Peart, a Democrat from Columbia, Md., said. “We can’t afford to lose the Senate.”
The case for Ms. Alsobrooks, 53, goes something like this: She is a charismatic candidate who will be able to unite and excite the party, driving women and Black voters to the polls. She is largely the choice of the state’s Democratic establishment and less prone to gaffes and mistakes than Mr. Trone, who has a more freewheeling style. Her history as a former prosecutor will appeal to tough-on-crime centrists in the general election. And, in a year in which abortion is expected to be a deciding issue, backers argue it is better to have a woman taking it on.
“As women, we don’t want people talking about us and making decisions about us without us,” Ms. Alsobrooks said in an interview.
The case for Mr. Trone, 68, centers on money but is also about cross-party appeal. With a fortune he made as the owner of Total Wine & More, Mr. Trone’s personal wealth would allow national Democratic organizations to devote their resources to more conservative-leaning states such as Montana and Ohio where the party has seats at risk, while the congressman could use his own money to defeat Mr. Hogan. In part because of his work fighting the scourge of opioids, Mr. Trone has also been consistently able to gain enough Republican votes from rural parts of the state to win in a swing district. And he is a more accomplished businessman than Mr. Hogan, a status that is expected to appeal to centrist voters concerned about management of the economy.
“This will probably be an expensive race,” Mr. Trone said in an interview, adding that his self-financing “will give them a lot more flexibility to spend money elsewhere.”
The race to replace Senator Ben Cardin, who is retiring after holding the seat since 2007, is now a dead heat. After leading in early polls, Mr. Trone is locked in a statistical tie with Ms. Alsobrooks, according to the latest survey from Emerson College. Both candidates have an early advantage in the poll over Mr. Hogan, a prized recruit of Senator Mitch McConnell, the Republican leader.
The race has turned nastier as the primary grows closer. A surrogate of Mr. Trone’s attacked Ms. Alsobrooks as needing “training wheels,” prompting 650 Black women to sign a letter condemning him. The congressman dismissively referred to Prince George’s elected officials who are supporting Ms. Alsobrooks as “low-level.” And Ms. Alsobrooks and her supporters have criticized Mr. Trone for using the word “jigaboo,” a disparaging term for a Black person, to describe a Republican theory about tax rates at a recent hearing. (In his apology, he said that he meant to say “bugaboo,” meaning a scaremongering tactic.)
“That’s why he’s a risky candidate in the general election,” Ms. Alsobrooks said in the interview. “He has made comments that are alienating to a large part of the base.”
Mr. Trone brushed aside that criticism. He conceded that he was rough around the edges, but said voters don’t care “if you’re not a smooth, polished, perfect speaker.”
“That’s what career politicians are,” he said. “I’m not a career politician.”
The two have also sparred over money. Mr. Trone accuses Ms. Alsobrooks of being beholden to special interest groups because she has accepted campaign donations from Exxon, Pfizer, Cigna, the National Restaurant Association and others.
Ms. Alsobrooks notes that Mr. Trone’s business has a history of giving money to right-wing politicians, such as Gov. Greg Abbott of Texas and Ken Paxton, the state’s attorney general, donations Mr. Trone describes as the cost of doing business.
“Now he talks about how he doesn’t accept money from super PACs, and all that kind of stuff — because he is one,” Ms. Alsobrooks said. “He is a super PAC. He forgot to mention that part.”
Neither is leaving anything to chance.
On a recent Monday, Ms. Alsobrooks was campaigning through Howard County with Calvin Ball, the county executive, pressing her case at senior centers, early voting spots where balloting was already underway, a library and a Whole Foods supermarket.
As he walked in to do some shopping, Sid Henkin, 79, of Columbia, told Ms. Alsobrooks he had already voted for her. He said he was influenced by seeing knowledgeable Democrats back her, including a friend who is involved in politics. “I’ll just admit that I followed the advice of someone I trusted,” he said.
The next day, Mr. Trone, also campaigning in sneakers with a suit, was working the crowd at an event at the B’nai Israel Congregation in Rockville. He told a rags-to-riches story of growing up poor, founding a business with hard work and earning a fortune.
That evening, he held a Get Out the Vote rally at a movie theater complex in Silver Spring with Representative Adam Schiff, Democrat of California and a leading candidate for Senate. Mr. Schiff, who achieved hero status on the left as he led the first impeachment of Mr. Trump, pitched Mr. Trone as a progressive who could work with Republicans.
“To protect our democracy, we must make the economy work for people, and having someone like David who has experience in business, who understands what it takes — the risk, the difficulty, the challenge of meeting payroll, who has used his success to help others — he can help us address not only the challenges to our democracy, but also the challenges to our economy,” Mr. Schiff said to applause.
The top Democrats in the House have weighed in to endorse Mr. Trone, including Representative Hakeem Jeffries, the minority leader, and the No. 2 and No. 3 House Democrats, Representatives Katherine M. Clark of Massachusetts and Pete Aguilar of California.
State Senator Jill P. Carter of Baltimore said she was backing Mr. Trone because she thought he was more of an outsider who wasn’t controlled by anyone.
“She’s a machine politician,” Ms. Carter said of Ms. Alsobrooks. “And that, for me, is the problem.”
Most of Maryland’s powerful politicians have lined up behind Ms. Alsobrooks, including all but one other Democrat in the congressional delegation. Representative Jamie Raskin, who has rallied with Ms. Alsobrooks, gave her a red, white and blue necklace to wear on the Senate floor once she’s sworn in. Senator Chris Van Hollen praised the way she successfully fought for the new F.B.I. headquarters to be in Maryland.
“Angela Alsobrooks played an important role there,” he said.
As Mr. Trone was trying to shore up support from fellow elected officials in the state, he went to see Representative Steny H. Hoyer, a top House Democrat who is a mentor to Ms. Alsobrooks.
“David Trone came in, and said to me, ‘I know you’re going to be for Angela,’ because everybody knows I’m close to Angela.” Mr. Hoyer said. “I pushed her. I supported her. And I think Angela is going to be our strongest candidate.”
Mr. Trone, he added, “could beat Hogan as well. But I told David, ‘There is not a single woman in the Maryland delegation. And I think it’s very important to have all segments of your population represented.’”
