BOSTON >> The deadline has arrived for Massachusetts residents who are eligible to vote in the state's presidential primary.

Secretary of State William Galvin says Wednesday is the final day to register for the March 1 election, and also the final day for registered voters to change their party status.

Voters registered as members of the Democratic, Republican or Green-Rainbow parties can vote only in the presidential primaries of those parties. Unenrolled voters can choose which primary they wish to vote in.

Galvin has cautioned about possible confusion over a fourth political party, called the United Independent Party. Voters registered in that party will not be able to vote in any other party primary on March 1.

Eligible voters can register online at , or by visiting their city or town halls.