Rep. Robin Smith resigns

Why it matters: Smith is one of the Republican leaders raided last year by federal agents. Rep. Glen Casada and his former aide Cade Cothren were also subject to searches.

Driving the news: A plea hearing is scheduled for Tuesday, March 8. The plea deal indicates Smith may be cooperating with the ongoing federal investigation.

• Casada has already said he will not seek reelection but is running for local office in Williamson County.

The latest: The federal investigation centers around a political mail company called Phoenix Solutions, which was allegedly set up by Cothren.

• A federal information document unsealed Monday says that Smith and Casada received kickbacks from Cothren in exchange for using their positions for official acts, including, "pressuring the Tennessee House Speaker's Office to approve Phoenix Solutions as a Mailer Program vendor and disburse State funds to Phoenix Solutions."