Sen. Michael Bennet (D., Colo.) knew about the White House’s Romanoff whispers:

Bennet told The Hill that he knew beforehand that White House Deputy Chief of Staff Jim Messina had reached out to Romanoff in hopes of avoiding a primary challenge to the incumbent Bennet. “Yeah, I was aware,” Bennet said. “Right.”
Bennet said he didn’t remember specifically how he was made aware of the contact, but pointed to a September 2009 Denver Post article about Messina’s contact with Romanoff. An aide clarified that Bennet also knew before the article’s publication of the White House contacting Romanoff.