Brian: I would definitely agree that Nixon was complicit, especially given his involvement in the “secret war” in Laos and Cambodia. However, Nixon also proved willing to go after Haiphong and Hanoi during Operations Linebacker I/II, and this had a huge effect on North Vietnam’s willingness to deal and thus bring the war to a close (for America, at least).
My larger point, and this directly centers on Obama’s prosecution of the war in Afghanistan, is that partisanship plays a far smaller role than politics and perception does (tying into your comment about hawks versus doves). There was an expression during LBJ’s administration that ran: “The Great Society died in the jungles of Vietnam”. Obama’s domestic agenda will, at some point, run directly into Afghanistan (and what’s left of the Iraq War) and I’d wager that Afghanistan will win.
Rightly or wrongly, Obama is being seen as ineffective on the domestic front (and lack of JOBS is killing him), and, at the same time, his base is feeling marginalized/disenfranchised by his so-called “adventurism” (Gore Vidal) in Afghanistan. Perception being the editor of reality, he is staring squarely in the face of a one-term presidency if he doesn’t turn things around and quickly. And, IMHO, pushing healthcare ain’t the answer.