Mexican officials were blindsided when they learned late Tuesday evening that Donald Trump, whom many of them detest, had accepted an invitation to visit with their country's president the following day.

El Universal, a major Mexican newspaper, wrote in an editorial Wednesday morning that Trump "caught Mexican diplomats off guard" by agreeing to meet with Mexican President Enrique Pena Nieto before Hillary Clinton had accepted Nieto's invitation.

Wednesday marks Trump's first meeting with a head of state since he launched his presidential campaign last June, during which he infamously described illegal immigrants crossing the U.S. border from Mexico as criminals and "rapists."

The Republican presidential hopeful's visit to Mexico City comes hours before he is set to deliver a highly anticipated speech about his immigration policy less than 200 miles from the southwestern border in Phoenix.

"I have accepted the invitation of President Enrique Pena Nieto, of Mexico, and look very much forward to meeting him tomorrow," Trump tweeted Tuesday night.

According to El Universal, Nieto did not want to meet with Trump this week as he has been busy working to finalize his annual report for congress. But Trump campaign officials eventually pressured him into agreeing to meet with the billionaire on Wednesday.

The meeting could become tense if a discussion of Trump's plan to build a wall along the U.S.-Mexico border occurs. Nieto has previously said there is "no scenario" under which the Mexican government would cover the cost of a border wall.

Trump's campaign manager, Kellyanne Conway, told NBC News on Wednesday that she expects to see a " very presidential Donald Trump" as he travels to Mexico to meet with the country's leader.