Let's say Kerry won the electoral college in 2004 but lost the popular vote to Bush (which was a very plausible scenario). Let's say Bush won 49.9% of the popular vote to Kerry's 49.1%. The GOP nominee would likely defeat Kerry in 2008 by a larger-than-1988 margin, given that Kerry would probably be a very unpopular incumbent. (I would see a Democratic victory in 2004 too late a POD to delay the financial tsunami...)
The GOP may gain a few seats in the Congress in 2006 but I still think the GOP, at best, could only manage to have no net loss of seats in Senate, more likely losing one or two seats. (Hey, tell me how you could get Rick Santorum re-elected?) The GOP at best could gain only one or 2 seats in 2008. I could see Democrats losing Louisiana, while the GOP retains Minnesota, Colorado, Alaska, New Hampshire, North Carolina, but not Virginia. Lautenberg will be vulnerable in TTL however, but he may pull it off narrowly.
When it comes to 2010, however, the OTL backlash towards Obama may happen to the GOP president as some sort of a reversal of 1994. The GOP will possibly lose both the Senate and the House, though perhaps a narrow loss in the House in this case given that the GOP would have gained seats in 2002, 2004 (in my scenario a gain of 1 or 2 seats still possible), 2006 and 2008 in TTL, which is insane - when did you see a single party gaining seats in 4 consecutive election

For Senate, a Democratic victory would be all but certain, at least it's much easier than for Republicans to regain the Senate in OTL 2010.
HOWEVER, is it possible for an anti-establishment, anti-war, socialist-leaning and uncompromising opposite of the OTL Tea Party among Democrats to primary incumbents and favorites, as well as pushing America towards the left in 2010? Who will be their leader? Perhaps Dennis Kucinich

, but anyone that makes more sense? Thoughts?