Polls have closed in Tuesday’s Pennsylvania primary election, which comes as a major test for Democrats eying to win control of the House this fall. Tonight's results will set the stage for what is largely seen as one of the country’s most contested congressional races.

The backdrop: Redistricting and a slew of resignations and retirements have created a wider playing field for Democrats who are likely to pick up more seats in the state where Republicans hold a 13-5 majority in the congressional delegation. Voters are also choosing nominees for governor and the U.S. Senate.