Saturday morning, from 10 a.m. to 12 noon Eastern, join Politics Nation on XM Radio's POTUS '08, when we'll tackle the week in politics. Listen free here (link about half-way down the page) as:

-- McCain campaign manager Rick Davis and Obama national campaign co-chair Eric Holder join Politics Nation to preview a possible general election matchup between two candidates who claim they can expand the map. What states are really in play this November?

-- Mississippi voters head to the polls to pick a new member of Congress. Is this another nail in the GOP's coffin, or can they use a win, even in heavily Republican territory, to start clawing their way back to the top?

-- And a host of top political writers sound off on the less appreciated moments that changed the Democratic primary race. Clinton's driver's license gaffe? Obama's "likable enough" fumble? We'll look back on the craziest sixteen months in American politics we've seen in generations.

All that and a few surprises, we're sure, Saturday morning on Politics Nation, only on XM Radio's POTUS '08. Listen live, Saturday from 10 a.m. to noon Eastern and again at 6:00 p.m. Eastern.