Iowa Sen. Tom Harkin, last seen harrumphing over the smallness of the final filibuster deal, will step aside after 30 years in office. Politico's quick spin, widely accepted, is that it "eases the burden on the GOP, who have to gain six seats to win the majority."
Sure, Democrats will have to spend more money to elect a new candidate than they were going to need to protect Harkin. Super PACs and 2016ers will have a fresh reason to irritate Iowans. But Iowa's become a tricky climate for Republicans. In 2010, the party generally recovered from the Obama wave, taking the governor's office and the state House of Representatives. The eventual governor, though, was Terry Branstad, a mainline conservative with a Soviet-like record of election victories. (He's now run the state for a total of 18 years.)
Branstad faced a primary against Bob Vander Plaats, the social conservative who has turned his perennial election losses into an unofficial gig as a kingmaker. Branstad only beat Vander Plaats by 9 points. In the non-binding 2012 caucuses, Vander Plaats endorsed Rick Santorum and helped him narrowly defeat Mitt Romney. As the year went on, conservatives campaigned hard—and expensively—to flip the state Senate and to unseat one of the judges who legalized gay marriage. They failed, and Democrats even cut the GOP's majority in the state House from 20 seats to 6 seats. But the right wasn't weakened at all.
All of this is to say that Iowa will be seen, by conservatives, as a fantastic opportunity to nominate a movement candidate—Rep. Steve King, maybe. The first test in this election may come for party leaders and organizations like the American Action Network and American Crossroads, which have hinted at backing "electable" candidates and stopping 'wingers from winning primaries.