Over the last couple of years, Mr. Swalwell’s profile has grown within Congress, as a member of the House Intelligence and Judiciary Committees, and as a frequent critic of President Trump on cable news.

Why is he running for president?

Mr. Swalwell told the Bay Area News Group that he comes “from a generation that solves big problems in the private sector but has lost faith that government can do it when it comes to health care, education and reducing gun violence.” That generation is the millennial one.

But Mr. Swalwell is far from the only candidate with relative youth on his side. Mayor Pete Pete Buttigieg of South Bend, Ind., is 37, for instance, as is Mr. Swalwell’s friend and House colleague, Tulsi Gabbard.

Mr. Swalwell has tried to differentiate himself with an aggressive stance on gun control (he has called for a national ban on assault weapons) and he has emphasized his experience as a prosecutor.

As The San Francisco Chronicle noted, Mr. Swalwell has also said his relationship with his conservative family would help him attract some of the president’s supporters.

Does he have a chance?

Mr. Swalwell’s path is pretty slim. He’s entering the race late, and beyond the cable news circuit, he’s not particularly well known. But Mr. Swalwell has said he will not run for Congress again while running for president, so he could be setting himself up for another try down the line.