FORMER PRESIDENT BARACK OBAMA waded into political races across the country on Monday, endorsing 260 Democratic candidates in 29 states, including six in Massachusetts.

Obama made a series of endorsements in August, but none of those was in Massachusetts. This time he backed Jay Gonzalez and Quentin Palfrey for governor and lieutenant governor, Ayanna Pressley for Congress, Tram Nguyen for the Massachusetts House, and incumbent Julian Cyr and newcomer Katie McBrine for the state Senate.

Aside from Pressley, who is headed for Congress because she is not facing a Republican opponent in November’s general election, the other endorsements can all be seen as Obama backing candidates who are either challenging Gov. Charlie Baker directly (Gonzalez and Palfrey), squaring off against his supporters in the Legislature (Nguyen and McBrine), or fending off a Baker-like GOP challenger (Cyr).

Nguyen is running against pro-life, conservative firebrand Rep. James Lyons of Andover, who has been endorsed by Baker. “I stand for inclusion, equality, and making sure that we have the quality of life we deserve in the district,” Nguyen told the Lowell Sun. “I stand polar opposite to my opponent in this race.”

McBrine, a pediatrician from Hingham, is challenging Sen. Patrick O’Connor of Weymouth, an ally of Baker’s in the Senate. McBrine said she favors a progressive, science-based policy agenda that includes single-payer health care.

Cyr, who worked as an intern in the White House in 2009, is facing a challenge from Barnstable Town Councilor John Flores. Flores, who says he is a Republican in the Baker mold, has criticized Cyr for being out of step with the district and for voting for a big pay hike at the start of 2017.

Nationally, Obama endorsed a number of progressive gubernatorial candidates, including  Andrew Gillum in Florida, Ben Jealous in Maryland, Gretchen Whitmer in Michigan, Michelle Lujan Grisham in New Mexico, and Christine Hallquist in Vermont. For the US Senate, Obama endorsed Kyrsten Sinema in Arizona, Bill Nelson in Florida, Tina Smith in Minnesota and Tammy Baldwin in Wisconsin. Nelson, Smith and Baldwin are incumbents, while Sinema is a House member.

One noteworthy Democrat absent from Obama’s list was Beto O’Rourke, the three-term congressman who is aiming to unseat Republican Sen. Ted Cruz of Texas in one of the most closely watched races in the country. “The liberal, 45-year-old O’Rourke has drawn crowds of thousands to his events — a rally Saturday night with country music legend Willie Nelson drew a reported 55,000 people — prompting no shortage of comparisons to the rock star aura that surrounded Obama during his campaign days,” the Washington Post reported.

Bruce Mohl oversees the production of content and edits reports, along with carrying out his own reporting with a particular focus on transportation, energy, and climate issues. He previously worked...