PORTLAND, Maine (AP) — Maine Democrats who have been scrambling to tap a new nominee for a pivotal U.S. Senate race against Republican Susan Collins are expected to nominate Troy Jackson at a last-minute convention this weekend.Jackson, a progressive Democrat, is a former president of the state’s Democratic-controlled Senate who has been a fixture in Maine politics for many years. He’s also a fifth-generation logger from a rural, heavily Republican northern part of the state.Jackson is expected to secure the nomination Saturday at a special nominating convention in Bangor that Democrats are holding after the implosion of primary winner Graham Platner’s campaign. Jackson would then have less than four months to campaign about Collins, who has been in the Senate for 30 years.Here are some things to know about Jackson:

He entered politics after leading a loggers’ blockade and was once a RepublicanJackson is well known in Maine politics, and his political affiliations and positions have evolved over the years. Most recently, he ran for the Democratic nomination for Maine governor this year but lost in the primary.He made his first run for office more than 25 years ago as a Republican, and was first elected to the Maine House of Representatives as an independent in 2002. He then switched to the Democrats in 2004 and served a total of three terms in the House.