Representative Mike Lawler, a New York Republican facing a tough re-election fight, disclosed on Wednesday that he was arrested on St. Patrick’s Day 2012 on suspicion of drunken driving, an incident that he has not made public in his previous campaigns for Congress or the State Legislature.

Mr. Lawler, 39, said in an interview with News 12 that the arrest took place in 2012, when he was executive director of the New York State Republican Party.

Mr. Lawler said he pleaded guilty in Rockland County to a reduced charge of driving with ability impaired, a violation. No public record of the arrest or disposition of the court case was made available by his campaign. A brief police blotter account, published in The Journal News, said the arrest occurred at 10:15 a.m. on the Palisades Parkway in Haverstraw.

In an interview with News 12, Mr. Lawler said that he had recently learned that his father was gravely ill. After drinking heavily in New York City, he said he was pulled over driving home on the Palisades.

“I was deeply disappointed in myself but moreover, disappointed that I let my dad down,” he said, noting that his father was a recovering alcoholic who had been sober for 20 years.

Mr. Lawler’s re-election bid in New York’s Hudson Valley is one of the most-watched House races in the country, with the swing district a focal point for both parties as they battle to control Congress.

The 17th Congressional District is one of the nation’s few remaining swing seats, with its voters supporting Kamala Harris in the 2024 presidential election even as they returned Mr. Lawler to Congress. This year, the Democratic candidate is Cait Conley, a national security expert and combat veteran who decisively won a heavily contested primary last month.

Ms. Conley, who has raised $1.6 million this cycle, according to her campaign, was recently named to Democrats’ competitive Red to Blue Program, which signals that the party will prioritize the race for fund-raising and strategic support.

She is hoping to harness voter frustration with the economy, Republicans’ cuts to benefit programs and broader concerns about the state of democracy to capture a seat that her party last held in 2020, when Mr. Lawler defeated Sean Patrick Maloney.

Mr. Lawler, who has tried to cultivate a political brand that is both moderate and broadly supportive of President Trump’s policies, added roughly $700,000 in the last cycle to his campaign war chest, which now tops $4.8 million — far more than Ms. Conley’s $1.3 million.

Mr. Lawler first revealed the drunk-driving arrest a few weeks ago during an appearance before a group of high school students in his district, where he spoke about the importance of road safety.

“There is never a justification to drive impaired,” Mr. Lawler said at the high school. The congressman, who previously received a “Legislative Hero Award” from the group Mothers Against Drunk Driving, is one of three House members who introduced the bipartisan Drunk Driving Prevention and Enforcement Act, which would require new vehicles to include breathalyzer technology, as well as provide additional funding to law enforcement with a goal of cutting down on drunken driving.