CHICAGO - President Barack Obama's re-election campaign has taken its digital infrastructure to the streets, arming its ground troops with mobile software that maps Democratic voters and canvassing strategies - and raising the blood pressure of privacy activists who worry about possible misuse.

The mobile application, which was publicly released last week, is a free download for use with an Apple iPhone. It re-purposes already public information about registered voters, such as their first name and last initial, age, gender and street address.

A version for Google's mobile platform, Android, was to be released on Thursday, the Obama campaign said.

Besides immediately being able to locate, register and tap nearby Democrats for cash - and send intel back to a database - the "Obama for America" app is essentially a portal to all things Obama. It will allow users to easily view and blast out to their social networks campaign announcements and find nearby political gatherings.

"We look at it as another great tool for our supporters to  get involved at the grassroots level," campaign spokesman Adam Fetcher said, adding that the Full-featured app's reception in field offices - and in the tech community - has been strong.

The app is helping hundreds of volunteers and staff with the voter drives that the campaign sees as a vital way to combat a crop of voter identification laws that could lower Democratic turnout in swing states and moneyed Super PACS flooding the airwaves with negative messaging on the sour economy.

But the implications of having a stranger's name and address  at one's fingertips has raised the hackles of privacy advocates, said Justin Brookman, a consumer privacy expert at the Center for Democracy and Technology, and their concern is not annoying pleas for cash.

"The concern is making it available to people who may have bad intent and that fear could deter people from giving money" or otherwise participating in the political process, Brookman said.

The Obama campaign said it takes privacy seriously and can take action against any wrong-doing.

"I think some people view this app as creepy but there is nothing illegal about what they are doing," said Lior Strahilevitz, a law professor at University of Chicago, where Obama taught constitutional law.

"They are aggregating a whole bunch of public records and using location-aware mapping technology. If a corporation or a political campaign wants to use that information and disseminate it in a useful way, there is no violation of American privacy laws," Strahilevitz said.

One voter quickly contacted using the app's information, Seattle-based software engineer James Hamilton, said he is excited to vote in November but does not appreciate the unsolicited attention.

"I don't value the direct marketing and don't want the interruption," said Hamilton.

Mitt Romney's campaign on July 31 released its mobile app, designed to inform supporters of the former governor's vice presidential running mate, an announcement expected any day. The campaign declined to comment on the app's possible evolution.

Roger Kay, a tech-sector analyst, said digital technology in politics is becoming an arms race as campaigns shower money on savvy programmers building upon already available technology.

"This is an ever-escalating technology war between both sides," Kay said.