BOISE, Idaho (AP) — A Boise lawyer plans to run as a Democrat for the U.S. Senate seat now held by Republican Jim Risch. Nels Mitchell aims to announce his run Tuesday at Boise's historic train depot. Mitchell grew up in Idaho's capital, but spent much of his professional career as a lawyer in New York and California. His legal experience includes several years as an associate regional director at the Securities and Exchange Commission in southern California, where he oversaw a staff of about 75 people who investigated and prosecuted securities fraud cases in the Los Angeles area. In Risch, Mitchell faces a foe who spent decades as a state legislator, lieutenant governor, fill-in governor in 2006 — and was elected to the Senate in 2008. He's now up for his first re-election.