Republican Rep. Tom Latham’s retirement announcement put another GOP seat into play for Democrats and capped off a wild day in congressional handicapping. He leaves behind the 3rd District of Iowa, which should turn into a good Democratic opportunity.

On Tuesday, not only did three members announce their exit, but three members in very competitive districts announced they would not seek re-election. GOP Rep. Frank Wolf’s 10th District in Virginia went from Safe Republican to Lean Republican, while Democratic Rep. Jim Matheson’s 4th District in Utah went from a Tossup to Safe for Republicans.

Latham’s district is also very competitive, particularly now that it is an open seat. Barack Obama won the district in 2012, 51 percent to 47 percent, and in 2008, 52 percent to 46 percent. President George W. Bush won it, 52 percent to 47 percent, in 2004.

In 2012, Latham defeated Democratic Rep. Leonard Boswell in convincing fashion, 52 percent to 44 percent, after Iowa lost a seat during reapportionment and Latham was left with few good options. Instead of facing Rep. Steve King in a primary, Latham chose to move and take on Boswell.

But now that Latham is on his way out, a crowd of Republicans is expected to take a look at the race. Candidates could come from out of the woodwork or jump down from the open-seat Senate race in order to run. On the Democratic side, former state Sen. Staci Appel initially ruled out a run for Congress but reconsidered her decision in July. But now that the seat is open, the Democratic field could change as well.

As we’ve said in Virginia and Utah, the candidate fields will need some time to take shape, and the national political environment is still uncertain. But for now, we’re moving Iowa’s 3rd District from Safe Republican to Pure Tossup in the Rothenberg Political Report/Roll Call ratings.

The Wolf, Matheson, and Latham decisions are a perfect example of why it is important to note that Democrats need a net gain of 17 seats to regain the House majority. Democratic strategists have been waiting for Virginia’s 10th District and Latham’s seat to come open for years. But because of Matheson’s decision, the best case scenario for Democrats is a net gain of a single seat from the three opens.