Donald Trump tweeted a word of thanks to House Speaker Paul D. Ryan's primary opponent for his "kind words" Monday, a notable shout-out that comes eight days before the primary in Wisconsin.

A Trump spokesman did not immediately respond to a request for comment on which words Trump was referring to in his tweet about businessman Paul Nehlen. But on his own Twitter feed Monday, Nehlen posted links to articles and pages on his campaign website that accuse Ryan of misrepresenting Trump's proposed Muslim ban and defend the mogul against Khizr Khan.

Khan, who is Muslim American and whose son Humayun Khan, an Army captain, was killed by a car bomber in Iraq in 2004, spoke out against Trump at the Democratic National Convention. Trump has said Khan had "no right" to go after him. He also suggested that Khan's wife, Ghazala Khan, was not allowed to speak at the convention, a claim she has denied.

Ryan, who has endorsed Trump but disagrees with his proposed ban on Muslims entering the U.S., issued a statement Sunday saying: "Many Muslim Americans have served valiantly in our military, and made the ultimate sacrifice. Captain Khan was one such brave example. His sacrifice — and that of Khizr and Ghazala Khan — should always be honored. Period.”

Both Republicans and Democrats are publicly responding to the row between GOP presidential nominee Donald Trump and Khizr Khan. Khan's son was killed while serving in Iraq. Here's what politicians from both parties said. (Monica Akhtar/The Washington Post)

On one of the campaign web pages Nehlen tweeted, his team writes: "The problem with Paul Ryan is his constant knee-jerk reactions to anything controversial Donald Trump might say without completely understanding the issue."

Ryan spokesman Zack Roday responded to Trump's tweet by saying in a statement: "Rather than engage in a back-and-forth, the Speaker is going to remain focused entirely on ensuring we deliver strong Republican majorities this fall."

Every message Trump posts has the potential to reach a broad national audience: He has more than 10.5 million followers on Twitter.