Nelsen set to seal Spurs switch
The move now paves the way for a surprise switch to Premier League high-flyers Tottenham Hotspur.
Spurs emerged as late contenders for the 34-year-old after Sebastien Bassong joined Wolverhampton Wanderers on loan.
No deal had been confirmed prior to Tuesday night's 23:00 GMT deadline, but having been released by Blackburn, the transfer window no longer applies to the versatile defender.
And his representative, Lyle Yorks, is confident that a deal can be reached between the two parties in the coming days.
"We settled with Blackburn and have reached agreement with Spurs," Washington-based Yorks told the Washington Post.
"We're just awaiting clearance. It's for six months, with a one-year option. It all unfolded quickly."
By Ben McAleer