Montgomery County Executive-elect Marc Elrich (D) in Rockville on Nov. 8, 2018. (Cal Cary/For the Washington Post)

Marc Elrich has some work to do.

He was elected with a decisive mandate Tuesday to lead Montgomery County, Maryland’s most populous — and one of its most economically powerful — jurisdictions.

But his progressive campaign drew attacks and sharp criticism from business and development leaders in the liberal suburb, who rallied around Nancy Floreen, a longtime Democrat who dropped her party affiliation to challenge Elrich as an independent. Floreen said Elrich, like herself a veteran County Council member, would be a “disaster” as county executive.

Now Elrich must repair relations with the business community as he prepares to govern a growing county of 1 million, where worries about the growth of the tax base and jobs intertwine with concerns about school overcrowding, traffic congestion and poverty.

He must also forge a relationship with newly reelected Gov. Larry Hogan (R), whom Elrich has criticized in the past — most recently on Facebook a few days before the election, when he wrote that the governor worked to stymie Democrats and didn’t do enough to distance himself from President Trump.

“In the state of Maryland, the governor’s office is a very strong, powerful office, and you need to find ways to work together,” said outgoing County Executive Isiah Leggett (D), who endorsed Democrat Ben Jealous in the governor’s race but has a close relationship with Hogan and refused to campaign against him. “The county cannot in and of itself govern in isolation.”

Democrat Marc Elrich, center, chats with Karen Brooks, left, secretary of the Democratic Club of Leisure World, and Elrich's driver, Clay Teunis, right, while campaigning at Leisure World in Silver Spring on Election Day. (Cheryl Diaz Meyer/For The Washington Post)

Elrich, who has not heard from the governor’s office since the election, said he has not said anything about Hogan that other Democrats haven’t.

“We’re both adults,” he said in an interview Thursday. “When the dust settles, you work with everybody. That’s exactly what I plan on doing.”

The vitriol of the campaign now in the past, Elrich says he is looking toward his transition — he has already sent out 180 invitations to be part of his team — and thinks his tenure will surprise those who didn’t support him. A former teacher who was backed by progressive organizations and unions, he said his door is open to everybody, including developers — if they offer to talk.

“Hopefully they’ll get a better understanding of what I want to do and be less panicked,” said Elrich, who won nearly two-thirds of the vote and finished far ahead of both Floreen and Republican Robin Ficker. “I think people will realize as I start doing stuff that I don’t have an extreme agenda.”

The candidates for Montgomery County executive, from left : Republican Robin Ficker, Democrat Marc Elrich and independent Nancy Floreen. (Bill O'Leary/The Washington Post)

Elrich addressed economic development in his victory speech Tuesday night as he outlined his platform: closing the “unacceptable” achievement gap in the county’s schools, enhancing ­early-childhood education, building bus rapid-transit routes — a system he proposed a decade ago — and examining the business climate in the county, which he said places too much emphasis on how to lure large corporations.

“We’re going to focus on small businesses,” Elrich told the cheering crowd, which at times erupted in chants of “Marc! Marc! Marc!”

“Because we all talk about how much small businesses contribute to building the regional economy or any economy,” he said, “and then our policies focus on how many tens of millions of dollars can I give to the biggest corporations in Maryland.”

Elrich also talked about the success of public financing — this election cycle was the first in which the county’s matching funds system was used — which enabled him to mount a campaign far larger than his previous efforts. And, he promised to use it again, for his next campaign.

“You don’t usually do this for one term,” he explained later.

Leggett said Elrich must combat the “perception” that he is anti-business — an idea capitalized on by Floreen and the developers who supported her.

“There is a perception, whether true or not, but a very serious perception that your focus is too narrow and does not include a broader base of concerns people have,” Leggett said of Elrich. “You have to find ways to clearly demonstrate to those who disagree with you, especially in the business community, that you are going to be the county executive to everyone.”

Some business leaders who endorsed Floreen are already sounding a conciliatory note, declaring that her candidacy was an “impossible task” in an overwhelmingly Democratic county where voters were determined to send a message to Trump.

Charlie Nulsen, chair of a super PAC that spent thousands criticizing Elrich, said he believes the new county executive understands that the county’s business climate needs to be improved. He also said he wasn’t worried about political fallout from opposing Elrich during the general election.

“I don’t think that’s the way Marc is, the way he will behave as an executive,” said Nulsen, who is president of Washington Property Co. in Bethesda. “I think we’re happy and would be welcome to sit at the table and see if there’s common ground to address these issues.”

Jeffrey Slavin, mayor of Somerset and a state Democratic leader who backed Elrich in the general election, said he saw “real growth” in the county executive-elect during the campaign. “I think he’s become a much better listener,” Slavin said.

He said Elrich has always been a favorite of the NIMBY crowd in his 30 years in political office — first as a Takoma Park City Council member, then as a three-term at-large County Council member. Now, he must expand and shift his focus as he prepares to be sworn in next month.

“I think one of the questions they have about him is whether he has the skill set to go from being a legislator to being an executive,” Slavin said. “I think people have seen a big change in him, even during the campaign, when he’s come to realize it’s a totally different gig to be the county executive than it is to be a left-wing member of the council.”