Todd Akin's aides are "making preparations" to quit the Missouri Senate race Tuesday, according to Richard Grenell, a Republican foreign policy aide who briefly worked for Mitt Romney. But that doesn't necessarily mean he's out. Akin said he's "not a quitter" on Mike Huckabee's radio show Monday (and reiterated that later on Twitter), but the interview didn't ease much of the pressure on him to drop out. Though Akin apologized for his rape comments, the list of Republicans telling him to quit the Missouri Senate race has been adding more and more names of greater and greater significance. Here are the Republicans giving up on Akin so far:

Update: Republican National Committee chair Reince Priebus said Akin has "got to think about" quitting the race, but did not explicitly say he had to drop out.

Update II: Mitt Romney said Akin should spend the next 24 hours to think over the race, National Journal reports.

Update III: Akin tells Sean Hannity, "I'm announcing today that we're going to stay in." He says he was told about the deadline to quit the race Tuesday at 5p.m., but he's not doing that.

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National Republican Senatorial Committee chair John Cornyn. The Texas senator said publicly that Akin's rape comments "wrong, offensive, and indefensible," and that  "over the next 24 hours, Congressman Akin should carefully consider what is best for him, his family, the Republican Party." That 24 hours part is really important -- Tuesday afternoon is the deadline for Akin to take himself off the ballot without a court order. And that was his public comment.

In private, the NRSC told Akin that if he doesn't quit, it won't support his candidacy, CNN's Dana Bash reports.

Crossroads GPS. The group Karl Rove founded is one of the most important outside spending groups this election. It is done with Akin, for now at least. After spending $5.4 million on ads in Missouri, it is pulling its ads in the state.

Massachusetts Sen. Scott Brown issued a statement saying, "As a husband and father of two young women, I found Todd Akin’s comments about women and rape outrageous, inappropriate and wrong. There is no place in our public discourse for this type of offensive thinking." He called on Akin to quit.

Wisconsin Sen. Ron Johnson tweeted, "Todd Akin’s statements are reprehensible and inexcusable. He should step aside today for the good of the nation."

Senate Minority Leader Mitch McConnell didn't explicitly call on Akin to quit, but said Akin should think over "whether this statement will prevent him from effectively representing our party," according to NBC News' Mike O'Brien.

UpdateThe National Review calls on Akin to quit:

People who make such remarks on television are typically capable of making more like them, or rather incapable of exercising the judgment to refrain. We suspect that this same lack of judgment will cause Akin to blow past tomorrow evening’s deadline for him to leave the race and allow the Republicans to select a better nominee. We hope the congressman, who surely wants to see a Senate with as much conservative strength as possible next year, will prove us wrong.

Others have condemned his comments -- the Mitt Romney campaign did so twice. But there are a few supporting him, like the Family Research Council.