House speaker candidates Maggie McIntosh and Dereck E. Davis. (Mark Gail; Linda Davidson/The Washington Post)

With a historic election for Maryland House speaker hanging in the balance, Del. Maggie McIntosh launched a public offensive Tuesday, promising an education-centric agenda and asserting she has the votes in hand to become the first woman and first openly gay person to lead a chamber of the General Assembly.

“I’ve got it,” the Baltimore City Democrat told reporters on a conference call. “I feel like it’s mine.”

But her rival, Del. Dereck E. Davis (D-Prince George’s), says he has the votes to win, from a minority of Democrats but also from Republicans, who hold about 30 percent of House seats. He said he will rely on support from both sides of the aisle in his quest to become the first African American House speaker in state history.

“People are going to do what they have to do to win,” Davis, 51, said in an interview. “If she indeed has the votes, I’d tip my hat and shake her hand,” he said of McIntosh. “I hope she’d do the same.”

Lawmakers will convene in Annapolis at noon Wednesday to elect a successor to Michael E. Busch, the state’s longest-serving speaker, who died unexpectedly on April 7.

The unusually public battle among two of his top lieutenants reflects a broader ideological divide in the Democratic Party nationally, as well as internal competition among key constituencies that include women, African Americans and the LGBTQ community.

Davis (D-Prince George’s), center, discusses the need to elect a black person as the next speaker during a news conference Friday in Baltimore. (Erin Cox/The Washington Post)

In Maryland, it has pitted liberals against moderates and severed long-standing alliances, alienating some black lawmakers from whites and splitting the Democratic caucus along generational lines.

Davis, a six-term lawmaker, is viewed as a centrist who is sympathetic to business interests. A majority of the divided Legislative Black Caucus on Monday rallied around him.

Liberal groups have buoyed McIntosh, conducting robocalls this week and threatening primary challenges against Democrats who back a candidate who wins the speakership by relying on Republican support.

McIntosh, 71, is seen as a tough negotiator and more in tune with the growing left wing of the party.

McIntosh (D-Baltimore City) at a legislative hearing last year. (Mark Gail/The Washington Post)

On Tuesday, she cast herself as a teacher whose goal in life and in public office is to close the achievement gap between white and black students. She promised to champion increased spending on education, expand access to affordable child care and require businesses to provide paid family leave.

“We are at a crossroads in the Democratic Party,” McIntosh said.

The House elects a speaker every January, at the start of the 90-day legislative session, which means that regardless of who is elected Wednesday, the other candidate could try to marshal majority support to stage an insurrection next year. McIntosh would not rule out such a move if Davis won the speakership on the basis of Republican support.

“I’m going to win as speaker with Democratic votes only,” she said. “I do not want to win with Republican votes.”

House Minority Leader Nicholaus R. Kipke (R-Anne Arundel), meanwhile, said his caucus will decide Wednesday morning on which candidate to support and will cast its 42 votes as a bloc. He said that many GOP lawmakers are smarting from “very insulting” social media posts from McIntosh supporters, who alleged the minority party was seeking to divide the Democrats in a power grab.

Despite rumors and reports to the contrary, Kipke said that neither Davis nor McIntosh has made promises about policies or chairmanships in exchange for GOP support and that he has not made any such requests.

“Those conversations never even happened,” he said. “The only things that we’ve asked for in this entire process . . . is for three things: fairness in the process, a seat at the table for all major issues and a speaker who will lead like they are the speaker for the entire House.”

While Davis has marshaled supporters before television cameras over the past few days, McIntosh’s team largely tried to whip votes out of public view. As the contest approached its final hours, however, she decided to join supporters in making her case to news organizations.

Her colleagues pitched her as a clever strategist who would be best-suited to advance the Democratic agenda, noting that as a committee chair she has treated Republican members with respect. “Maggie is a Democrat, no question about it,” said Del. Patrick G. Young Jr. (D-Baltimore County). “But she will be a speaker for the entire House.”

Todd Eberly, a political scientist from St. Mary’s College, said Democratic power struggles are especially fraught in Maryland because of the longevity of the state’s political leaders. Busch held the speakership for 16 years. Thomas V. Mike Miller (D-Calvert) has served as Senate president since 1987. As a result, some lawmakers have waited their entire careers to seek a higher post.

“Leadership opportunities come far too infrequently in Maryland,” Eberly said.

Both McIntosh and Davis promised they could repair the fracture if elected.

“It’s unfortunate that we’ve gotten to this point,” Davis said. “No one wanted this. I’m sure Chairman McIntosh didn’t want this. I didn’t want this. But the stakes are high. And when the stakes get high, nerves fray and people act in a way they normally would not.”