Tennessee Senator and Foreign Relations Committee chairman Bob Corker has announced that he will retire at the end of his current term:

Once considered an ally of Trump’s national security team, Corker traded insults with the president during the August break amid chatter that staunch conservatives would mount a primary challenge to the Senate Foreign Relations Committee chairman.

Corker’s retirement will touch off what is likely to be a highly contested, ideologically driven primary. It also creates a vacuum among Senate Republicans for leaders on national security issues. For now, Corker isn’t planning on getting involved in either contest.

Corker spent two terms in the Senate, and during that time he had a generally poor record on foreign policy issues. He was one of a handful of Republicans willing to vote to ratify New START in one of his few good decisions, but for the most part the possibility that he would be a voice for pragmatism and realism in foreign affairs went unrealized. The longer that Corker was in the Senate, the more conventionally hawkish he became.

While Iran hawks blamed him for not doing more to oppose the nuclear deal, he was a vocal opponent of the deal and a co-sponsor of an unfortunate piece of legislation that could still end up helping opponents of the deal to derail it. The Corker-Cardin bill is the most significant piece of legislation that bears the senator’s name, and it is likely to be used by Trump to begin the process of reneging on U.S. commitments under the JCPOA. Corker distinguished himself in a bad way by being remarkably supportive of the Saudi-led war on Yemen despite his evident lack of understanding of the geography and politics of the region.

It would be tempting to celebrate Corker’s retirement, but any Republican in a position to replace him as chairman on Foreign Relations is not going to be an improvement. Todd Young and Rand Paul have shown impressive leadership in opposing U.S. support for the war on Yemen, but neither of them is going to be Corker’s replacement. Whoever takes Corker’s place is probably going to be even more hawkish and ideological than he was.