I just got off the phone with former Sen. John Danforth (R-Mo.), who shed a little light on his surprising endorsement of Rep. Roy BluntRoy Dean BluntGOP group's ad calls on Graham to push for election security: 'Are you still trying?' Exclusive: Kushner tells GOP it needs to unify behind immigration plan The Hill's Morning Report - Can Trump save GOP in North Carolina special election? MORE's (R-Mo.) Senate candidacy last week.

Danforth had been backing Washington University law professor Tom Schweich in the GOP primary, and Schweich was all ready to run until backing out last week. The former senator's very public promotion of Schweich was seen as a slight to Blunt at the time.

I tried to press him on why he endorsed a Blunt so soon after actively promoting a candidate to run against him, and Danforth suggested he was merely advocating for his law partner.

"I was thinking, at the time, that there was some advantage to having a totally fresh face running for the Senate," Danforth said. "But I think he made the right decision that we would be better off as a party without a primary fight than with one."

Danforth also had praise for Blunt.

"I think it's clear that Roy Blunt's going to be our nominee, and looking at his record, considering what he has been and done in Congress and his knowledge of the issues, I think he will do a very good job of sharing the message of the Republicans," Danforth said.

Asked his impression of former state Treasurer Sarah Steelman, who could still challenge Blunt in a primary, Danforth said only, "fine."