If Allen wins narrowly, he's still probably finished as Presidential matter.
Back in '96, Congressman Jim Ross Lightfoot challenged Sen Tom Harkin in Iowa's Senate race.
Harkin's name was occasionally bounced around as possible Presidential material.
Harkin won 54-46% - but was perceived afterwards to be damaged goods because he didn't decisively destroy Lightfoot.
Good point. A damaged candidate for senator isn't in a good position. But then, NO senator is in a good position to win the presidency. Unfortunately, HRC is different in so many ways that the model doesn't work for her. Although I would'nt be surprised if we have two senatros for the ultimate party noms this time, either.