President Barack Obama has taken the unusual step of endorsing Democratic statehouse candidate Juliana Stratton in her primary bid to unseat a fellow Democrat, Chicago state Rep. Ken Dunkin.

Obama recorded radio and television ads endorsing Stratton and saying she will “stand up for our children, our seniors and our working families.” The ads were announced Monday.

The contest between Dunkin and Stratton is seen as a proxy battle between Republican Gov. Bruce Rauner and Democratic House Speaker Michael Madigan. Rauner supports Dunkin and Madigan’s union allies support Stratton because Dunkin has voted against pro-labor measures.

Obama told Dunkin to “sit down” during a speech to Illinois lawmakers earlier this year when Obama said voting with the other party didn’t make someone a sell-out. Dunkin had stood and applauded.