President Trump attacked Democrats and said they would let undocumented immigrants “overwhelm” communities, in an election-eve pitch meant to energize his base amid signs of trouble for some GOP candidates.

Speaking at a rally in Fort Wayne, Ind., Trump criticized Rep. Maxine Waters (D-Calif.) and, without offering evidence, said Democrats would allow immigrants to “overwhelm your schools, your hospitals and your communities” if the party took control of Congress.

At his final stop in Cape Girardeau, Mo., Trump showcased his close ties to Fox News personalities, giving Sean Hannity a live interview before the event, praising Laura Ingraham as she began her 10 p.m. show and calling Hannity and Jeanine Pirro to the stage to praise him. He said Democrats want to make the United States a “giant sanctuary for gang members and MS-13 killers,” referring to the criminal gang.

Trump’s final swing through Ohio, Indiana and Missouri focused on states that will be key to the new Senate majority. The president has acknowledged that Democrats could win the House, where they need a net gain of 23 seats. GOP officials and strategists voiced cautious optimism Monday about keeping the Senate, where Democrats need a net gain of two seats, but were less confident about keeping the Republican majority in the House.

At stake Tuesday is control of Congress, 36 governorships and hundreds of down-ballot races nationwide.

Both parties spent the day delivering their final message to voters and closely monitoring the handful of battleground races that will determine control of the House and Senate.

At a Northern Virginia campaign rally, former president Barack Obama said the election will define the soul of America, as other Democrats accused Trump of fearmongering.

“The character of this country is on the ballot,” Obama said, his voice hoarse from a flurry of campaign stops around the country. “The politics we expect is on the ballot. How we conduct ourselves in public life is on the ballot.”

In Missouri, Trump rallied supporters with the aim of boosting the Senate campaign of Republican state attorney general Josh Hawley. GOP strategists had watched nervously in recent days as Hawley’s race against incumbent Democratic Sen. Claire McCaskill appeared to tighten.

With no early-voting option in the state, the outcome will be decided by how voters feel Tuesday.

Trump struck an upbeat tone Monday, saying he believes Republicans will do “very well” in both the House and Senate contests. He framed the vote as a referendum on his presidency and said his one regret is that he “would like to have a much softer tone,” before attacking Democrats at his campaign rallies hours later.

Trump also said that he is not worried about Democrats subpoenaing and releasing his tax returns if they win the House.

“I don’t care,” Trump told reporters. “They can do whatever they want, and I can do whatever I want.”

Republican leaders have been confident about flipping a Senate seat in North Dakota, where GOP Rep. Kevin Cramer has led incumbent Democratic Sen. Heidi Heitkamp in polling.

But there was far less certainty about the likely outcomes in other competitive contests. GOP operatives noted that the broader political mood in some battleground races seemed to be moving in Democrats’ favor, at least marginally.

House Speaker Paul D. Ryan (R-Wis.) also said he was “cautiously optimistic” about the GOP’s chances of keeping the lower chamber, though he acknowledged that his party faces head winds.

“History is not our friend,” Ryan said Monday on Fox News, noting that a first-term president’s party loses 32 seats on average. “... We already are standing against the historical trend that cuts against us.”

The Justice Department announced Monday that it would deploy personnel to 35 jurisdictions in 19 states to “monitor compliance with voting rights laws,” a move that was viewed with suspicion and alarm by voting rights advocates.

Trump also tweeted that law enforcement was “strongly notified” to watch for illegal voting and that anyone “caught” would be subject to the “Maximum Criminal Penalties allowed by law.”

Trump has been just as aggressive on immigration, calling the migrant caravan slowly headed toward the U.S.-Mexico border an “invasion.”

Last week, he ordered more than 7,000 active-duty troops to deploy along the border in Arizona, California and Texas, and released a campaign ad that was later pulled off the air by NBC News and Fox News. CNN refused to air the ad, calling it racist.

The 30-second television spot features images of Luis Bracamontes, an undocumented immigrant who was convicted of killing two sheriff’s deputies in California in 2014, and the migrant caravan.

“Stop the caravan. Vote Republican,” the ad concludes.

Cynthia Jurado, a 22-year-old political independent from Des Moines, said Monday that she’s voting against Republicans in part because of this kind of rhetoric on immigration.

“Nowadays I see a lot of racism,” she said. “My family experienced some of it as well. This started happening after the presidential election, and I don’t think people should have to fear.”

Trump said Monday he did not know the ad had been pulled. When a reporter said the ad had been described as “offensive,” he shot back: “A lot of things are offensive. Your questions are offensive.”

Some areas of the country are already experiencing unprecedented turnout as the clock ticks toward Tuesday morning.

In El Paso, the 12-day early-voting period that ended Friday saw 139,000 residents cast ballots — more than three times the 2014 early-voting turnout. The town has historically had among the lowest turnout rates among major U.S. cities, but it is now on track to at least double its total 2014 turnout of 82,000 votes.

El Paso is home to Democratic Rep. Beto O’Rourke, whose challenge to Republican incumbent Sen. Ted Cruz has drawn national attention and a cascade of cash from both parties’ donors.

Minnesota has seen a similar jump in voter numbers, with more than 539,000 ballots cast so far, a whopping 129 percent increase from 2014. Secretary of State Steve Simon, a Democrat, tweeted that the state was “on the verge of shattering the old record by surpassing the raw total for 2016.”

Both Trump and Obama have campaigned especially hard in Georgia, where the close race for governor has drawn national attention.

Democratic candidates continued to grapple with political fallout from a “hacking” investigation into their party that was launched at the last minute on Sunday by Georgia’s secretary of state, who also happens to be the Republican gubernatorial candidate.

Neither Brian Kemp’s office nor his campaign has provided evidence that Democrats tried to hack the voting system.

Stacey Abrams, the Democratic gubernatorial nominee, also spent Monday morning addressing a racist robo-call mocking Oprah Winfrey, who campaigned for her last week.

“This is the magical Negro Oprah Winfrey asking you to make my fellow Negress Stacey Abrams the governor of Georgia,” the robo-call begins, before spewing nearly 60 seconds of racism and anti-Semitism.

Anne Gearan in Macon, Ga.; Robert Moore in El Paso; Alex Schuman in Des Moines; Felicia Sonmez, Sean Sullivan and Cleve R. Wootson Jr. in Washington; Torey Van Oot in Eagan, Minn.; and Vanessa Williams in Augusta, Ga., contributed to this report.