Donald Trump announced on Tuesday night that he had accepted an invitation from President Enrique Peña-Nieto to visit Mexico today in advance of his speech on immigration.

CNN:

A meeting between Trump and Peña Nieto would be extraordinary, given Trump's continued pledges to build a wall on the border with Mexico and make Mexico pay for it. Trump has also stoked fierce criticism in Mexico and in the Hispanic community at large for his at-times inflammatory rhetoric in discussing illegal immigration.

 The Washington Post first reported Trump was mulling a meeting with Peña Nieto before Trump confirmed it.

At a Tuesday night rally, Trump stuck to his tough-talking rhetoric.

"We are also going to secure our border and stop the drugs from pouring in and destroying our country. And I'll be talking about that tomorrow night in Arizona, big speech on immigration," he said in Everett, Washington.

The visit follows months of warring words between Trump and Mexico's leaders, including when Peña Nieto compared Trump to brutal dictators Adolf Hitler and Benito Mussolini.

Trump in the early months of his campaign also leveled unfounded accusations that the Mexican government was intentionally sending its unwanted citizens across the border and into the United States.

But both Trump and Peña Nieto have publicly expressed a willingness in recent weeks to meet with one another.

"Mrs. Hillary Clinton and Mr. Donald Trump, I would like to express to both of them my greatest respect, my deepest respect. And from right now, I propose going into a frank, open dialogue with whomever is elected," Peña Nieto said in July during a joint news conference with President Barack Obama at the White House.

This is a fascinating twist that presents an unknown dynamic into the campaign.  Trump's legendary ability to shmooze and win over people will be put to the test with Nieto.

The Mexican president is a wily politician with far better political skills than Trump.  Given the rhetoric that has flown back and forth between the two, the possibility that Nieto is laying a trap for Mr. Trump cannot be dismissed.  The level of dislike of Trump in Mexico is very high.  He is seen as public enemy #1.  It is entirely possible that Nieto will ambush Trump, using his own words to pander to the anti-American, anti-Trump elements in Mexico.

They won't be agreeing about much.  There is a chasm between them that suggests that either Trump will offer a dramatically different plan on immigration later today when he delivers the speech, or Nieto will heavily criticize Trump in any statement after the meeting.  Nieto has already indicated he opposes the wall, he refuses to even consider paying for it, and he will continue to push Mexican citizens to cross the border illegally into the U.S.  These are all policies popular with the Mexican people, so Nieto has no reason to change them. 

Trump, on the other hand, needs to alter the perception that he is anti-Mexican and anti-immigration.  That's a tall order, given his past statements.  But softening his positions will lose him votes only with his base, making it vital that his speech this afternoon hit the bullseye.

With the Nieto meeting and the immgration speech. today marks one of the critical days of the campaign.