Obama campaign manager Jim Messina said his campaign "can do both things both persuade the undecideds and get out our voters."
The Democratic campaign also says a deeper look at the registration numbers shows an uptick in new Hispanic voters and voters under the age of 30 voting blocs where the president has an advantage.
Obama's registration and get-out-the-vote operations in 2008 played a crucial role in his getting elected. With the White House race tightening less than four weeks from Election Day, the Democratic campaign is banking on its organization in the battleground states to give Obama an edge.
Deadlines to vote in the November election have passed in many states, but the registration totals are expected to shift somewhat in the coming days as last-minute entries are counted.
The most current data, available from state election boards, give Democrats a registration advantage in most of the battleground states with party identification: Florida, Iowa, North Carolina and Nevada. The party also significantly outpaces Republican registration in Pennsylvania by more than 1 million voters. That's part of the reason Romney's campaign has not made a serious effort to compete in the state.
Republicans have a voter registration advantage in Colorado and New Hampshire.
Voters in three other battleground states Ohio, Virginia and Wisconsin do not register with a party when they sign up to vote.
Of course, voter registration totals don't tell the whole electoral story in many states.
That's been particularly true in North Carolina, where there have long been more Democratic voters than Republicans. This year, the Democrats have a 790,000 voter advantage.
But many registered Democrats in North Carolina cast their presidential ballots with the GOP. Obama's narrow victory there in 2008 marked the first time a Democrat won the state since 1976. And about one-fourth of registered voters in the state are registered independents.
Republicans are touting their success in cutting into Democratic registration leads. In Iowa, for example, there were more than 100,000 more Democrats on the voters rolls when Obama won the state in 2008. This year that margin has dropped to just under 13,000.
Obama's campaign says it is already making up for that decline by aggressively ensuring Democrats on the rolls get to the polls, particularly during early voting. According to the campaign, 50,000 more Democrats than Republicans have already cast their votes by mail and in person.
Aides to the president are also buoyed by increased battleground state registration among Hispanics and young people, key sources of support for Obama.
Since August, the campaign says about half of new registrants in most battleground states have been under the age of 30. Hispanic registration is also up this year in every key electoral state except Ohio.
State by state data shows Hispanics have increasingly registered as Democrats since 2008.