A joke made by Sen. John McCain (R-Ariz.) about Iranian President Mahmoud Ahmadinejad has been criticized as "racist" by Rep. Justin Amash (R-Mich.).

McCain tweeted about Ahmadinejad's offer to be the first Iranian sent into space, linking it to last week's report that the country successfully put a monkey on a rocket.

The crack earned McCain some blowback on Twitter. When he protested, Rep. Amash responded:

Coming from these two politicians, the intraparty dispute is not too surprising. McCain is known for speaking his mind on Twitter -- he has used the medium to take shots at Russian President Vladimir Putin. And Amash, who is of Syrian and Palestinian descent, is outside the GOP establishment. The libertarian-leaning House member backed Rep. Ron Paul (R-Tex.) in last year's presidential election and voted against House Speaker John A. Boehner (R-Ohio) in last month's leadership election.