Florida Gov. Ron DeSantis’ decision to send two planes last week filled with Venezuelan migrants from San Antonio, Texas, to Martha’s Vineyard, Massachusetts, has been met with its first law enforcement challenge.

The San Antonio-area sheriff announced Monday that he had opened a criminal investigation into the circumstances surrounding the Republican governor's operation to transport roughly 50 migrants to Martha’s Vineyard.

In a news conference on Monday on the migrant flights, Bexar County Sheriff Javier Salazar said that his office was investigating whether the migrants were victims of crimes after they were “lured” from the county’s migrant resource center, flown to Florida and then taken to Martha’s Vineyard.

“There’s a high possibility that the laws were broken here in the state of Texas in Bexar County,” Salazar said.

"As we understand it, 48 migrants were lured -- I will use the word 'lured' -- under false pretenses, into staying at a hotel for a couple of days …They were taken by airplane, at a certain point they were shuttled to an airplane where they were flown to Florida and then eventually flown to Martha's Vineyard again under false pretenses,” he said.

His office said in a tweet that they are working with advocacy groups and private attorneys representing the migrants and were “preparing to work with any federal agencies that have concurrent jurisdiction, should the need arise.”

“We’re going to discover what extent the law can hold these people accountable,” Salazar said.

Gov. Ron DeSantis' communications director, Taryn Fenske, responded to the investigation on social media Monday night, contrasting the migrants who went through Florida with others who have traveled in Texas.

"Immigrants are more than willing to leave Bexar County after being enticed to cross the border and ‘to fend for themselves.’ FL provided an opportunity in a sanctuary state w/ resources, as expected - unlike the 53 who died in an abandoned truck in Bexar County in June," Fenske wrote.

-- ABC News’ Miles Cohen

At a rally in Youngstown, Ohio, on Saturday night on behalf of GOP Senate nominee J.D. Vance ahead of the midterms, former President Donald Trump came out defiant against the numerous investigations into him while continuing to rally his base against his political enemies.

And though Trump was in Ohio to rally support for Vance ahead of “the most important midterm election in U.S. history,” he also took a swipe at his candidate while trying to tout the power of his own endorsement.

“J.D. is kissing my a--, he wants my support so bad!” Trump said to laughter from the crowd.

Trump addressed Vance's previous criticism of him, saying that was “before he knew me and then he fell in love”-- which Trump likened to his relationship with North Korean dictator Kim Jong Un.

The former president -- who has been teasing an expected 2024 presidential bid -- made a number of influential endorsements in GOP primaries this year, even as some in his party, like Maryland Gov. Larry Hogan, said Trump's candidates would be weaker in the general election.

Trump has used his popularity with primary voters to target some of his Republican critics, including House members who voted for his impeachment or local lawmakers who didn't back his false 2020 election claims.

Labeling opponents, including those investigating him, as “thugs and tyrants,” Trump said at Saturday’s rally that they “have no idea of the sleeping giant that they have awoken” -- just days after he warned there would be “big problems” if he were to be indicted.

Among the notable probes against him is a federal case over his handling of what the government says was highly classified and sensitive material that Trump took with him after leaving office. He denies wrongdoing.

And just days after Sen. Lindsey Graham introduced a bill for a federal 15-week abortion ban, Trump reiterated his support for leaving it up to the states -- and warned that Republicans should “get smart” on the issue.

-- ABC News' Olivia Rubin

Dr. Mehmet Oz, the GOP Senate candidate in Pennsylvania, ended a three-stop campaign swing on Monday by driving off with several Philadelphia residents who told him they were dealing with drug addictions -- with Oz then heading to reserve spots at a detox center.

The trip was unplanned, Oz told ABC News.

"The solution is this: Getting people to detox. It's going to fail a lot of times, but it's going to succeed a lot as well," Oz told reporters ahead of their departure for the centers, with the residents in a white pickup truck.

After scheduled events in Germantown, Kensington and McPherson Park, the former surgeon and talk show host spent roughly 20 minutes at a park in Kensington, dubbed the "BadLandz" by residents due to its high crime rate, speaking with community members, some of whom were bystanders who approached Oz and told them they used drugs.

"Do you want help?" Oz asked one man, who identified himself to ABC News as Robert Alvord.

"I need help," responded Alvord, who said he'd lost family members to overdoses.

Oz gave him a drug overdose treatment to have on hand and pointed to community leaders he'd assembled as resources.

"Detox saves lives, but the first step is often the most difficult," Oz tweeted after the interaction, along with an ABC News clip of him driving off with the residents.

--ABC News' Will McDuffie

Virginia Republican Gov. Glenn Youngkin will venture to Arizona next month for another midterm campaign stop -- he’ll stump for Kari Lake, the most MAGA-aligned GOP candidate he’s been a surrogate for thus far.

Youngkin -- whose state does not allow consecutive gubernatorial terms -- has been building a national profile through midterm campaign appearances -- sparking talk of a potential 2024 presidential bid even before his halfway point in office.

A date for Youngkin's visit in Arizona is not yet set, but expected the week of Oct. 17, Lake’s spokesperson confirmed to ABC News following reports from Politico. Over the past few weeks, Youngkin has traveled to Michigan for the state's GOP nominating convention, Nevada -- an early state on the 2024 GOP nominating calendar -- and Maine -- to attend a fundraising event for gubernatorial candidate Paul LePage. He’s also headed to Kansas later this week.

Additional states Youngkin is slated to travel to ahead of this year's elections include Georgia, New Mexico and Oregon, all of which have competitive governor races this year.

Youngkin’s upcoming political and fundraising events for Lake will likely focus on education policy, an issue that propelled him into office last year and remains one of Lake’s campaign centerpieces.

–ABC News’ Libby Cathey and Hannah Demissie

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