Democrat Ed Markey defeats Republican Kevin O'Connor for a US Senate seat in Massachusetts

• Incumbent Massachusetts Sen. Ed Markey is projected to win against the Republican challenger Kevin O'Connor.
• Polls closed in Massachusetts at 8 p.m. ET.
• Markey defeated Rep. Joe Kennedy in the Democratic primary election.
• Hillary Clinton won Massachusetts by 27.2 points in 2016.
• See the live coverage and full results from the US Senate elections.

Incumbent Democratic Sen. Ed Markey will retain his US Senate seat in Massachusetts in the race against the Republican Kevin O'Connor, Decision Desk HQ and Insider have projected.

Markey joined the Senate in 2013 after John Kerry became the secretary of state under President Barack Obama. He handily defeated his challenger for the Senate seat in 2014, Brian Herr, by 22.8 points.

After a hard-fought battle, Markey defeated Rep. Joe Kennedy in the Democratic primary by 10.9 points.

In the 2016 presidential election, Hillary Clinton won Massachusetts by 27.2 points.

Sabato's Crystal Ball at the University of Virginia Center for Politics rated the race as "safe" Democratic.