After three months of merger talks, Pillsbury Winthrop and Washington, D.C.-based Shaw Pittman have reached the due diligence phase, according to a source close to the discussions.

Pillsbury spokeswoman Crystal Rockwood said she could neither confirm nor deny the report, adding that the firm has talked with numerous possible merger partners but had nothing to announce. “We’ve been open that we’ve been exploring and having talks [with firms],” Rockwood said.