Washington (CNN) Two California House Republicans headed for the exits this week as a blue wave builds ahead of this year's midterm elections. Here are three groups of Republicans whose retirements could further shake up the House map. Rep. Fred Upton of Michigan surprised Republicans in November by dropping a Senate campaign to run for re-election in his perennially competitive Kalamazoo-based House district. He's the only Republican left representing a House district in New England. Other potential game-changersA number of younger, popular House Republicans represent districts that Clinton won.

Source: CNN January 13, 2018 13:07 UTC