California Gov. Gavin Newsom on Thursday continued his ongoing duel with red state governors, championing liberal policies on abortion and immigration in the face of some Republican leaders' moves on those issues.

Newsom, who is speculated to be a potential 2024 presidential contender (which he has played down), used his gubernatorial reelection campaign funds to place advertisements in six states with limited abortion rights after the Supreme Court’s June decision in Dobbs v. Jackson Women’s Health Organization, overturning Roe v. Wade.

All of the Newsom-funded billboards advertise that California is ready to help residents who are seeking an abortion.

“You do not need to be a California resident to receive abortion services,” one billboard said.

In a tweet on Thursday, Newsom announced that he would be responding to Florida Gov. Ron DeSantis and Texas Gov. Greg Abbott having transported immigrants to Martha’s Vineyard in Massachusetts and to Washington, D.C. -- which DeSantis and Abbott say is in protest of Democratic border policies -- by requesting the Department of Justice investigate their efforts.

“I’m formally requesting the DOJ begin an immediate investigation into these inhumane efforts to use kids as political pawns,” Newsom wrote in a tweet, accompanied by the his request, addressed to Attorney General Merrick Garland.

Newsom has shot proverbial arrows at DeSantis before -- in August sending money across the country to help Florida Democratic gubernatorial nominee Rep. Charlie Crist defeat DeSantis this November.

-- ABC News' Isabella Murray

Two days ago, Don Bolduc won his race to be New Hampshire's GOP Senate nominee after months of making false claims that the 2020 election was stolen from Donald Trump the centerpiece of his campaign.

On Thursday, he made a 180-degree turn after beating the more moderate state Senate President Chuck Morse. Trump-endorsed Bolduc said he's now taking a "definitive" stance that Joe Biden's presidency is legitimate.

"I've come to the conclusion, and I want to be definitive on this: The election was not stolen," Bolduc said on Fox News, even while noting he still believes there was evidence of fraud. "Elections have consequences and, unfortunately, President Biden is the legitimate president of this country," he said.

The retired Army brigadier general said he came to his conclusion after talking to voters and doing his own research.

-- ABC News' Hannah Demissie

Continuing her rare break from her GOP border state allies on immigration, ​Arizona gubernatorial candidate Kari Lake says she's "not a fan" of Florida Gov. Ron DeSantis flying two planes of undocumented immigrants to Martha's Vineyard, Massachusetts.

Though careful not to mention DeSantis by name, Lake told Fox host Tucker Carlson Wednesday night it is "just taking people here illegally who shouldn't be here, moving them further inland."

Even so, Lake said, she "got a kick" out of the recent stunts by DeSantis and Texas Gov. Greg Abbott.

"Watching these liberal mayors just throw their hands up and say, 'We can't handle it,' because it's life every day for us in these border states," she said.

"My husband and I are saying that all the time, send them up to Martha's Vineyard," 80-year-old Yuma, Arizona, resident Sandy Fisher told ABC News.

-- ABC News' Libby Cathey in Arizona

What could be one of the most consequential midterm elections in recent history has seen an equally dogged primary cycle. Republicans and Democrats are sparring over every seat in the House of Representatives, 35 Senate seats and 36 governorships.

The stakes could not be higher with the ups and downs of the Biden presidency, the growing investigation into the Jan. 6 insurrection, the Supreme Court's decision to overturn Roe v. Wade abortion rights and inflation running at historic highs. Candidates who support Donald Trump’s false claims that the 2020 election was stolen will appear on ballots in nearly every state in November.

ABC News has seven reporters embedded in key swing states across the country so readers can get on-the-ground accounts of what candidates are doing and voters are saying.

Welcome to Trail Buzz, an ABC News blog that brings you all the twists and turns from the midterm campaign trail.

Get live updates on campaign news and key reads and analysis from ABC’s reporters. We’ll link to excerpts from the Hulu streaming series "Power Trip" featuring ABC's campaign embeds, the smart takes from FiveThirtyEight, our "Democracy in Peril" series and the sharp political analysis each morning in "The Note."

Senator Elizabeth Warren, D-Mass., is expected to campaign on Oct. 26 for Wisconsin Gov. Tony Evers, Lt. Gov. Mandela Barnes and state Attorney General Josh Kaul in what is the latest appearance by a prominent Democrat to rally voters weeks before the high-stakes midterms.

The events with Warren, first reported by ABC News, will also feature Wisconsin's Democratic senator, Tammy Baldwin.

Baldwin, Evers, Kaul and Warren will host an early voting event focused on young people near the campus of the University of Wisconsin at Madison, according to the Wisconsin Democratic Party.

Baldwin and Kaul are expected to walk with a group of students to an early voting location to cast their ballots.

Barnes is in a tight race to defeat incumbent Sen. Ron Johnson, a Republican.

Polling shows that Evers is in a toss-up race, too, against Republican challenger Tim Michels, with the latest FiveThirtyEight average showing Evers with less than 1% lead.

In a statement to ABC News, the Wisconsin Democratic Party Chair Ben Wikler said: "This election is deadlocked, and no one can sit this out. If Wisconsin students turn out to show the GOP they won’t let them trample on their rights, Democrats will win up and down the ballot. Senator Warren is an electrifying voice who will bring her incomparable energy and vision to mobilize Wisconsin students at exactly the moment it’s needed most."

In her own statement, Warren said, "Voters in Wisconsin know what is at stake in this election. Wisconsinites have the opportunity to vote for [Senate nominee] Mandela Barnes, Tony Evers, and Democrats all the way down the ballot who will fight to restore a woman’s right to choose, to bring down costs, to build an economy that works for all of us, and to attack the climate crisis head on. I’m proud to join them in this critical fight."

Warren joins a growing list of big-name Democrats -- including former President Barack Obama -- to hit the trail in various battleground states before Election Day.

They hope to counter the history of rough midterm elections for the party in power, plus major headwinds like high inflation, in part by focusing on Republican-backed restrictions on abortion and the extremism of some of the GOP nominees.

When asked by reporters after a gubernatorial debate on Friday whether former President Donald Trump planned to stump for the Republican ticket in Wisconsin, Brian Fraley, a communications specialist for the Michels campaign, said they would notify the press if such an event was scheduled.

Fraley said then that Obama coming to Milwaukee was a "sign" that the Evers campaign was "in trouble" because "they're calling in all the big dogs."

-- ABC News' Cheyenne Haslett and Paulina Tam