MEXICO CITY -

Donald Trump is headed to Mexico, making a surprise visit Wednesday to meet with the president of a nation he derided at the start of his White House campaign as a source of rapists and criminals coming to the U.S.
    
The trip, a politically risky move 10 weeks before Election Day, puts Trump in a country where he's widely despised alongside a foreign leader who has compared him to Adolf Hitler. It also comes hours before the Republican presidential nominee delivers a highly anticipated speech in Arizona about illegal immigration, a defining issue of Trump's presidential campaign, but also one on which he's appeared to waver in recent days.
    
The visit follows an invitation from President Enrique Pena Nieto, but protests are expected. Both a former Mexican president and first lady bluntly told the billionaire New Yorker that, despite Pena Nieto's hospitality, he's not welcome.
    
"We don't like him. We don't want him. We reject his visit," former Mexican President Vicente Fox told CNN, calling the trip a "political stunt." Added former first lady Margarita Zavala on Twitter: "We Mexicans have dignity, and we reject your hate speech."
    
After saying during his Republican primary campaign he would use a "deportation force" to expel all of the estimated 11 million people living in the United States illegally," Trump suggested last week he could soften that stance. But he still says he plans to build a huge wall - paid for by Mexico - along the two nations' border. He is under pressure to clarify just where he stands in a speech that's been rescheduled several times as he and his staff has sent varied and conflicting messages on the issue.
    
"The American people are going to see more clearly that there's one candidate in this race who's prepared to take the steps necessary to end the flood of illegal immigration," Trump's running mate, Indiana Gov. Mike Pence, said Wednesday on CNN.
    
Trump will also make clear, Pence later told CBS, "that there will be no path to legalization, no path to citizenship. People will need to leave the country to be able to obtain legal status or obtain citizenship."
    
The buildup to the speech was abruptly interrupted Tuesday night by the news that Trump would make the visit, accepting on short notice an invitation offered last week by Pena Nieto. The newspaper El Universal wrote in an editorial that Trump "caught Mexican diplomats off guard."
    
Even before the Mexican trip was announced, former adviser Barry Bennett said Trump faced political risk should he appear to be reversing himself on an issue as sensitive as immigration.
    
"After you've said all these things, you can't say, 'I didn't mean it,'" Bennett said. "You run a bigger risk of losing supporters you have than possible gains on this issue."
    
Trump has promised, if elected, to deport millions of immigrants who are in the United States illegally, force Mexico to build a wall to secure the nearly 2,000-mile border and renegotiate the NAFTA trade agreement to make it more favorable to the United States.
    
He responded to Vicente Fox's criticism on Twitter, saying the former president had, like Pena Nieto, invited him to come. Fox shot back with a tweet of his own, saying he had invited Trump to "come and apologize to all Mexicans. Stop lying! Mexico is not yours to play with, show some respect."
    
Pena Nieto made his invitation to both Trump and his Democratic rival, Hillary Clinton, who met with him in Mexico in 2014. The inclusion of Trump puzzled many in Mexico, who said it wasn't clear why their own unpopular president would agree to meet with someone so widely disliked in his country.
    
Mexico City-based security analyst Alejandro Hope suggested that Pena Nieto "wanted to invite Hillary, but that meant inviting both of them, and nobody thought Trump would accept first."
    
Pena Nieto has been sharply critical of Trump's immigration policies, particularly the Republican's plans to build a wall and have Mexico pay for it. In a March interview, he said that "there is no scenario" under which Mexico would do so and compared Trump's language to that of dictators Hitler and Benito Mussolini.
    
He had a different tone late Tuesday, tweeting, "I believe in dialogue to promote Mexico's interests in the world and, principally, to protect Mexicans wherever they are."
    
New Jersey Gov. Chris Christie, a close Trump adviser, has been among those pushing him to make the trip, according to a person familiar with their conversations. Christie made his own successful trip to Mexico City in September 2014 and has a warm relationship with the Mexican president.
    
On NBC's "Today," Trump's campaign manager, Kellyanne Conway, was asked Wednesday if Trump would change his rhetoric in his meeting with Pena Nieto. She said, "I think you'll see a very presidential Donald Trump."
    
Clinton's campaign, meanwhile, urged voters to not get distracted by Trump's visit to Mexico or "be fooled" by what it called his attempts to disguise his immigration policies.
    
"What ultimately matters is what Donald Trump says to voters in Arizona, not Mexico, and whether he remains committed to the splitting up of families and deportation of millions," said campaign communications director Jennifer Palmieri.