Live updates: Candidates in Maine Senate and three governor’s races to debate tonight

What to know today TONIGHT'S DEBATES: Several general election debates are being held tonight, including in the toss-up Senate race in Maine between Republican incumbent Susan Collins and Democrat Troy Jackson, and the governor’s races in Michigan, Georgia, and Iowa. TRUMP HEADS TO BALTIMORE: President Donald Trump is heading to Maryland today to announce that the Navy and the defense company Anduril Industries will invest $6.6 billion for a new factory to build submarine parts. LATE AD DELUGE: Republicans are swamping House and Senate races with an unprecedented flood of late ad spending as the party tests whether hundreds of millions of dollars can buy it some reprieve from the eroding political environment that’s threatening longtime Republican states and districts. KANSAS SENATE RACE: NBC News chief data analyst Steve Kornacki analyzes the surprisingly tight race for Senate in Kansas between Republican incumbent Roger Marshall and Democrat Adam Hamilton in this week's subscriber-exclusive newsletter, The Data Dive.

Live updates and the latest news as Republicans swamp House and Senate races with late ad spending and a survey of government officials finds political polarization is spiking in local communities around the country.