According to MSNBC just now, White House counsel Fred Fielding offered Democrats interviews with Karl Rove and other White House officials, but the testimony would be unsworn, behind closed doors, and no transcript would be permitted.
Both House and Senate Democrats already plan to vote on issuing subpoenas later this week.
Update: On CNN, Sen. Chuck Schumer (D-NY) just told reporters that “[Fielding] said he wanted this to be a conversation rather than a hearing. A conversation’s fine. But let’s have a conversation under oath with a transcript so we can see what has happened and weigh the testimony of these particular witnesses against the others…. Mr. Fielding indicated that he did not want to negotiate, but that doesn’t mean we’re not going to try.”