Former President Barack Obama announced his second wave of midterm election endorsements Monday as his presence increases just over a month out from Election Day.

Headlined by Sen. Bill Nelson, D-Fla.; Alexandria Ocasio-Cortez, a New York progressive congressional upstart; and Andrew Gillum, the progressive Democratic gubernatorial nominee in Florida; Obama made 260 endorsements Monday in races where he believes his support could make a “meaningful difference.”

“The Democratic Party has always made the biggest difference in the lives of the American people when we lead with conviction, principle, and bold, new ideas. Our incredible array of candidates up and down the ticket, all across the country, make up a movement of citizens who are younger, more diverse, more female than ever before,” Obama said in a statement. “They’re Americans who aren’t just running against something, but for something. They’re running to expand opportunity and restore the honor and compassion that should be the essence of public service.

“I’m proud to endorse so many of them today, and I’m eager to continue making the case for why they deserve our votes this November,” he added.

The former president endorsed four candidates running for Senate, including three incumbents — Nelson; Sen. Tammy Baldwin, D-Wis.; and Sen. Tina Smith, D-Minn. The lone challenger he backed is Rep. Kyrsten Sinema, D-Ariz., running for the seat being vacated by retiring Sen. Jeff Flake, R-Ariz.

Obama also threw his support behind a group of gubernatorial candidates, headlined by Gillum and Tony Evers, the Democratic nominee in Wisconsin who is looking to unseat Gov. Scott Walker.

The mass endorsement announcement comes on the heels of his initial round of 81 endorsements revealed in August.

The 44th president has also increased his travel on behalf of candidates, having made trips to California, Illinois, Ohio and Pennsylvania. He has also headlined fundraisers for Democratic groups.