YARMOUTH — Former teacher Zak Ringelstein announced he is a candidate for the Democratic nomination for U.S. Senate. 

The 2018 Senate election in Maine will take place Nov. 6, with the primary election on June 12. 

Democrat Benjamin Pollard, of Portland, announced in December that he is also a candidate to challenge incumbent U.S. Sen. Angus King, who is seeking his second term.

Republican Sen. Eric Brakey of Auburn, Republican Max Linn of Bar Harbor, Libertarian Chris Lyons of Brunswick and independent Alex Hammer of Bangor have also announced bids.