The newest state legislator in Oklahoma leaned over his bathroom sink, teasing his tousled hair to get that John F. Kennedy bouffant. The blue suit came from J.C. Penney and fit snugly; the tie was tied tight.

“My hair keeps standing up because I’m already sweating so much,” said Jacob Rosecrants, a 39-year-old single father. “When you go campaigning, no one expects you to look like this. But when you win, everyone expects you to look like this.”

A month before, he was a middle school geography teacher driving a Chrysler PT Cruiser with no air conditioning, knocking on doors at the end of a hot Oklahoma summer. Now, he is the poster boy for a national party desperate to rebuild its bench.

Rosecrants is a Democrat who won in a district that is 60 percent Republican. He is one of three Democrats who have won GOP legislative districts in Oklahoma special elections in the months since President Trump won 65 percent of the vote in one of the country’s most conservative states.

National Democratic Party leaders have rejoiced over these victories — along with five other recent wins in Iowa, New Hampshire and Florida in districts that had voted for Trump — as evidence that the chaotic presidency may be creating opportunities for Democrats to capture more seats in next year’s state and congressional elections. “A beacon of hope,” said Jessica Post, executive director of the Democratic Legislative Campaign Committee, the party’s strategy arm for legislative races.