Missouri Gov. Jay Nixon (D) today endorsed Rep. William Lacy Clay in his Democratic primary fight against Rep. Russ Carnahan.

The endorsement was a significant boost for Clay.

“For over 25 years, Lacy Clay has been a powerful voice for working families and a tireless advocate for the people of St. Louis,” Nixon said in a statement released by the Clay campaign. “And throughout his long career in public service, I’ve considered Lacy a close personal friend. He’s the right man to continue serving the people of the 1st Congressional District and I fully support his re-election.”

After redistricting, Carnahan’s district was essentially eliminated. He was drawn into Clay’s district, and despite strong entreaties from national Democrats not to cause an intraparty battle, Carnahan decided to take on Clay.