A busy week of Senate debates starts Tuesday in Maine, where Republican Sen. Susan Collins faces Democrat Troy Jackson in the first of four debates. The others are set for Oct. 8, 13 and 15. Tuesday is also the eighth anniversary of Collins' vote to confirm Justice Brett Kavanaugh, The Washington Times notes.

The race is close. The RealClearPolitics polling average had Jackson at 47.5% and Collins at 47.3% as of Oct. 1, the Washington Examiner reports. Collins has beaten bad polls before. In 2020, surveys showed her behind, and she won by 9 points. More than $185 million has been spent in the race, AdImpact says.

Jackson joined the race late. He replaced Democrat Graham Platner, who dropped out after a rape allegation, The Washington Times reports. A CBS poll found 53% of Democrats and independents wished they had another choice.

Other debates follow quickly. In Iowa, Republican Rep. Ashley Hinson and Democrat Josh Turek meet Wednesday on Iowa PBS for the seat Joni Ernst is leaving. On Thursday, Michigan's Abdul El-Sayed and Mike Rogers debate in Grand Rapids, and Georgia Sen. Jon Ossoff faces Republican Rep. Mike Collins. Alaska Sen. Dan Sullivan and Mary Peltola debate next Thursday. In Minnesota, Michele Tafoya and Peggy Flanagan meet Friday.

New polls show more seats in play. In Kansas, a New York Times/Siena poll has Republican Sen. Roger Marshall tied with Democrat Adam Hamilton at 45% each. Kansas has not elected a Democratic senator since 1932. In Michigan, a Mitchell Research poll taken Oct. 1 shows Democrat El-Sayed at 45.6% and Republican Rogers at 41.4% among likely voters. About 11% of Michigan voters said they had already voted by absentee ballot.

Republicans hold the Senate 53-47, so Democrats need a net gain of four seats for a majority. RealClearPolitics rates nine races as toss-ups, KMBC reports. Election Day is Nov. 3.

Iowa's debate airs on Iowa PBS. Early in-person voting in Michigan starts Oct. 24.

What we know: Polls are close in several states that Republicans now hold.
What we don't: Whether debates shift any of these near-tied races.