Democratic presidential candidates Hillary Clinton and Bernie Sanders are organizing in Pennsylvania as some Republican Party leaders are shifting their support in the contested primary.
Pennsylvania's April 26th primary is four weeks away, and voter registration is now closed with just over 4 million Democrats and more than 3 million Republicans.
State figures show that Democrats raked in more new voters in 2016, but more voters switched their registration to Republican. Both are down slightly from surges in 2008.
Secretary of the Commonwealth Pedro Cortés said last-minute registrants weren't alone. About 200,000 people filed their paperwork in the five weeks leading up to Monday's deadline. Cortes said more than one-quarter of those signed up last week alone.
Since the state's online voter registration portal opened in August, about 600,000 people have registered to vote for the first time or updated their information, Cortés said. Of those, about 110,000 people were Democrats or Independents who switched party affiliation to Republican and about 80,000 were Republicans or Independents who switched party affiliation to Democrat.
"It's interest in the candidates and the different platforms, but in the larger scheme of things ... you're still talking about a small percentage, less than 5 percent," he said.
Pennsylvanians will weigh in on the Republican and Democratic primaries for president, and pick party nominees for Congress, state attorney general and state Legislature.
State records show about 8.2 million registered voters live in Pennsylvania, but Cortés said analysts with the Pew Research Center and others have estimated more like 10 million people actually qualify.
Pennsylvania's closed primary system requires voters to select a party affiliation in order to vote in that party's primary. Only those registered for one of the two major parties "will have a voice," Cortés said.
Sanders and Clinton now have offices open in Pittsburgh, Scranton and Harrisburg. Meanwhile, Ohio Governor John Kasich is picking up more support from the party elite now that the GOP presidential field has narrowed to three.
Cortés said state officials are shooting for a 70 percent participation rate in 2016 compared to the 63 to 65 percent of registered voters who showed up in recent years. Voter participation peaked in 1992 at about 82 percent, he said.
Pennsylvanians will weigh in on the Republican and Democratic primaries for president, and pick party nominees for Congress, state attorney general and state Legislature.
Online registration for the general election in November is available at everyone.votespa.gov. For those who have an existing record with the Pennsylvania Department of Transportation like an identification card or driver's license, the process takes eight to 10 minutes, Cortés said.
The Associated Press contributed to this report.