The messages are the first written records from Mr. Ensign documenting his efforts to find clients for Mr. Hampton, a top aide and close friend, after the senator had an affair with his wife, Cynthia Hampton. They appear to undercut the senator’s assertion that he did not know the work might involve Congressional lobbying, which could violate a federal ban on such activities by staff members for a year after leaving government.
The e-mail messages also hint at what Mr. Ensign’s office now says was an effort by the Las Vegas firm, a small energy investment business called P2SA Equity, to improperly link Mr. Ensign’s possible assistance to a promised donation.
The F.B.I. and the Senate Ethics Committee are investigating whether Mr. Ensign, in trying to contain the fallout from his affair with Ms. Hampton, conspired to find lobbying work for her husband despite the federal restrictions. They are also examining a $96,000 payment Mr. Ensign’s parents made to the Hamptons.
Mr. Hampton has said that the senator promised to work around the lobbying ban and help him make up the income that he and his wife, a former Ensign campaign staff member, lost when they left their jobs after the affair ended in 2008.