“I want to use the opportunity to strongly encourage the many young people I meet to consider public service,” said Frelinghuysen in a written statement announcing his retirement Monday morning. “Public service is an incredible way to turn your convictions into something that serves the greater good and to do it alongside people from every walk of life and background.”

Frelinghuysen is the 33rd GOP member of Congress this cycle to decline to seek another term. His announcement follows the retirement of scandal-plagued Pennsylvania Rep. Pat Meehan, as well as that of former Utah Rep. Jason Chaffetz — who resigned before completing his term — and Tennessee Rep. Diane Black, who is running for governor.

Frelinghuysen was likely to be one of the most vulnerable Republicans on the map, in a district Trump won by a hair. According to the UVA Center for Politics Crystal Ball, New Jersey’s 11th Congressional District has now moved to a toss-up.

Yet his decision to leave comes as something of a surprise. Just three weeks ago, when The Hill asked whether he had plans to leave Congress, he replied, “Certainly not.”

And yet Frelinghuysen, one of the only Republicans to vote against the tax scam, appears to understand the dire electoral situation for House Republicans, who are facing widespread voter anger and a record number of Democratic challengers.

Whatever happens in November 2018, the ranks of the old guard GOP leadership will be severely depleted.