WASHINGTON — (CNN) Donald Trump faces one of the most crucial days of his campaign Wednesday as he travels to Mexico to visit that country’s president and then heads to Arizona to deliver a highly anticipated speech that will seek to clarify his controversial immigration policy.

The speech is expected to lay out a range of policy prescriptions to stem the tide of illegal immigration and follows a week during which Trump and his campaign publicly wrestled with how to handle the more than 11 million undocumented immigrants living in the US.

It’s an especially fraught moment for the Republican nominee because he surged to victory in the primaries with hardline rhetoric against illegal immigration, including a pledge to deport all undocumented immigrants.

But he appears poised to strike a more moderate tone that could appeal to suburban white voters in the general election without alienating his base.

Trump began his week of public handwringing on the issue by vowing last Monday that he was “not flip flopping” on immigration, but that he was looking to “come up with a fair but firm process.”

The next day, he told Fox News’ Sean Hannity that “there could certainly be a softening” of his deportation policy and suggested his administration would “work with” undocumented immigrants, rather than deport them — which would mark a major flip-flop.

But two days later, he told CNN’s Anderson Cooper that he would offer “no path to legalization” and suggested deportation was back on the table.

Meanwhile, his campaign scrapped plans for Trump to deliver his immigration speech last Thursday in the battleground state of Colorado and then dismissed reports Trump speak on immigration Wednesday in Phoenix, until Trump tweeted he would in fact deliver the speech there.

Democrats have seized on Trump’s refusal to disavow his mass deportation plan, while Trump’s most right-wing supporters have struggled to save face amid the real estate mogul’s waffling. And some moderate Republicans have cautiously embraced Trump’s apparent tone shift.

Trump’s campaign has remained tight-lipped on the content of the speech, but Trump’s son Donald, Jr. said Monday on CNN that the speech won’t address every aspect of Trump’s immigration policy but that the campaign would “continue to lay things out in the coming weeks and months.”

But any distance Trump takes from his proposal to deport all estimated 11 million undocumented immigrations via a “deportation force” would mark a major flip-flop on the very issue that drew many Trump supporters to the billionaire’s brazen outsider candidacy.

“They’re bringing drugs. They’re bringing crime. They’re rapists. Some, I assume, are good people,” Trump said launching his candidacy last summer.

Within weeks, he was vowing to deport all undocumented immigrants.

“You’re supposed to come in legally. I would get people out and I would have an expedited way of getting ’em back into the country so they can be legal,” Trump told CNN’s Dana Bash in July. “We will find them, we will get them out.”

But it’s possible Trump will glaze over the fate of the 11-plus million undocumented immigrants living in the US in his speech Wednesday despite hammering his bold plans to deport them all throughout the Republican primary — a policy position that drew millions of Republican primary voters to his campaign and helped Trump cast his opponents as weak, ineffective and tied to the failures of Washington.

While rarely raising his deportation plans, Trump has consistently and vociferously pledged his commitment to building a border wall, leading his supporters in a boisterous call-and-response chant of “Who’s going to pay for the wall?” to a resounding “Mexico!”

Trump’s campaign surrogates in recent days have slammed the media for focusing on those 11 million people, instead touting Trump’s commitment to first deporting undocumented immigrants who have committed crimes in the US and his plan to build a wall on the border with Mexico, and make that country pay for it.

And they have also rejected the notion that Trump is softening his stance — despite Trump using that specific word last week.

“He wasn’t softening on anything. He didn’t change his stance on anything,” Donald Trump, Jr. told Cooper on Monday, adding that Trump’s policy on deportations has “been the same.”

Former Texas Gov. Rick Perry asserted Monday on Fox News that “Donald Trump’s not softening his position on immigration.”

“I think there’s a lot of talking heads that try to get, you know, ‘I’ll grab a word here, I’ll grab a word there.’ Donald Trump is going to secure that border,” he said.

Trump’s speech comes at a critical juncture for his candidacy, which has stared down deficits in every major national poll in the last month as well as in a slew of polls in key battleground states.

Trump has sought to flip his fortunes by shaking up his campaign leadership — ditching his campaign chairman Paul Manafort in favor of hiring a new campaign manager and chief executive — and ramping up outreach to minority communities, notably African-Americans and Hispanics.

In doing so, Trump has argued that those minorities have been the most affected by undocumented workers taking low-wage jobs and by the crime Trump claims undocumented immigrants have contributed to society — despite lacking the evidence to back up a connection between undocumented immigrants and higher crime rates.

Hispanic leaders and Republicans mindful of the party’s need to draw in Hispanics to remain competitive in years to come have stressed the need for Trump to move beyond his deportation policy proposal and begin addressing other ways to deal with the undocumented population.

Asked whether “building the wall or doing something with the 11 million here illegally” was more important, Trump’s new campaign manager Kellyanne Conway didn’t hesitate.

“It’s absolutely building the wall,” she said.