2016:
Mark Kirk/Huntsman vs. Joe Sestak/Mike Capuano
2020:
Joe Sestak/Mike Capuano vs. Ryan Frazier/Kay Bailey Hutchinson
2024:
Ryan Frazier/Justin Reynolds(pm of +6,+2 from New Hampshire, Representative) vs. Populist Bro/Leftist Guy
This could happen but for this scenario to work I made some odd things happen. In an oil crisis Sestak pledges to use synthetic oil to relieve the crisis. Kirk opposes this in an odd twist and this is when the GOP starts attracting more young moderates along with Kirk's moderate image. Frazier becomes an environmentalist(for a Republican) and barely wins the nomination on the strength of the youth. He doesn't do well among blacks but barely wins due to the stagnant nature of the tech industry with so many subsidies going to the Rust Belt.
Yeah this is really unrealistic.