WESTPORT — Early voting gets underway Monday in primaries for the Republican nominations for the U.S. Senate and 4th Congressional District.

A week of early-voting sessions precedes the official April 13 primary.

The winning candidates will take on Democratic incumbents in both races on the Nov. 5 ballot.

Vying for the GOP’s Senate nominations are Gerry Smith, the first selectman of Beacon Falls, the endorsed candidate, who is being challenged by Matthew Corey of Manchester, who lost a contest six years ago to Democratic U.S. Sen. Chris Murphy.

Murphy is seeking election to a third term this year.

Contenders in the 4th Congressional District primary are the endorsed candidate Bob MacGuffie of Fairfield, a former leader of the Tea Party movement, and Michael Goldstein of Greenwich, who lost a primary for the district’s nomination two years ago.

The winner will take on U.S. Rep. Jim Himes, a Democrat running for a ninth term.

Primary voting is open only to registered Republicans.

In Westport, all early-voting ballots will be cast in Room 107 of Town Hall, 110 Myrtle Ave.

The schedule of early-voting sessions is:

Monday, Aug. 5: 10 a.m. to 6 p.m.

Tuesday, Aug. 6: 8 a.m to 8 p.m.

Wednesday, Aug. 7: 10 a.m. to 6 p.m.

Thursday, Aug. 8: 8 a.m. to 8 p.m.

Friday, Aug. 9: 10 a.m. to 6 p.m.

Saturday, Aug. 10: 10 a.m. to 6 p.m.

Sunday, Aug. 11: 10 a.m. to 6 p.m.

On Tuesday, Aug. 13, the official primary date, votes will be cast from 6 a.m. to 8 p.m. in the town’s standard polling stations.

For questions, contact the Registrars of Voters office at 203-341-1117.