Rick Bowmer/AP Photo

WASHINGTON - Mitt Romney today double-downed on his promise to reduce the country's unemployment rate if elected  in November, again offering  a specific 6 percent target that he says he'll achieve during his first term in office.

"I can tell you that over a period of four years by virtue of the policies that we put in place we'll get the unemployment rate down to 6 percent or perhaps a little lower, depends in part upon the rate of growth of the globe as well as what we're seeing here in the United States," Romney said in  an interview with Time magazine's Mark Halperin.

The current U.S. unemployment rate is 8.1 percent.

Earlier this month, Romney said that any unemployment rate "over 4 percent is not a cause of celebration." The candidate first vowed to reduce  unemployment 6 percent last fall during in a speech at a North Las Vegas trucking depot. Romney said he would lower the then-9.1 percent unemployment rate to 5.9 percent by the end of his first term as president.

The candidate also repeated his benchmark 5.9 percent goal repeatedly in a 161-page book that outlined his economic plan.

In a conference call with reporters, Obama campaign press secretary Ben LaBolt accused Romney of "moving the goal post" on his promise regarding the unemployment rate.

"He said he was going to get it down to 4 percent several weeks ago and now he's at 6 percent, and he's already moved the goal posts on a critical promise he's made," said LaBolt.

Romney could still be overreaching: The Congressional Budget Office has already published its unemployment rate estimate for the end of 2016, and it's 6.3 percent.