Jane Norton, the former lieutenant governor of Colorado, is the latest Republican to launch a challenge to appointed Democratic Sen. Michael Bennet in his 2010 bid for a full six-year term.

The Denver Post reported Tuesday that Norton, Colorado’s No. 2 officeholder from 2003 to 2007, filed papers to establish a campaign committee and plans to make an official candidacy announcement next week.

Norton has set up a campaign Web site and is taking other steps to promote her candidacy online. Typing “Michael Bennet” in Google displays Norton’s campaign Web site address as a “sponsored link.”

While Norton’s previous statewide stint likely will make her a top-tier candidate for the GOP nomination, she joins a field already crowded with six other would-be Republican challengers, who have revealed tentative or official plans to run.