MARGARET WARNER: In addition to the hours of public arguments in the senate over witnesses, there have been extensive negotiations behind the scenes. Some insight into both now from Boston Globe columnist Tom Oliphant and National Journal columnist Stuart Taylor, who is also a contributor to Newsweek.

MARGARET WARNER: Tom, the Senate is behind closed doors debating this. Why has this witness dispute become such a big issue in these proceedings?

TOM OLIPHANT: Because I think, Margaret, it is a metaphor for how long is this trial going to last. I don’t think witnesses per se have importance. I think the claims on both sides today made it clear that no one is saying that somebody is going to come forward and say something dramatic. But rather than argue about the specific length of the trial, witnesses have in a sense become the metaphor. What’s happening now I think has been arranged inside the senate Republican family. It appears to be working in the sense that it will have a majority. But it makes the House managers livid.

MARGARET WARNER: Why does it make them livid?

TOM OLIPHANT: Because they feel that their opportunity to put on the kind of trial that could have persuaded the senate, that could have persuaded public opinion has been limited to the point of ineffectiveness. And their expressions of frustration on the floor today and yesterday, but particularly yesterday, I think are just the surface of a genuinely deep fury at having the rug pulled out from under them.

MARGARET WARNER: Do you agree, Stuart? I mean, they made an incredibly passionate case for these three but they’re livid about it and they feel they need more.