Hughes wins in 1916, making him president during the war and peace treaty.
Come 1920, Hughes is unpopular (though not to the extent that Wilson was in OTL) and as a result, a conservative democrat (Mccadoo? Mitchell Palmer?) wins the presidency, going on to serve 2 full terms. Their VP is elected in 1928 and has the missfortune of being in office during the start of the Great Depression.
1932 sees the Republicans (under Herbert Hoover or Theodore Roosevelt JR, perhaps) reclaim the Whitehouse, implimenting something not too dissimelar to the New Deal.
From there, the parties proceed, with the Republicans as the more progressive party.