Gov. Janet Mills announced today that she is suspending her campaign for U.S. Senate, ending speculation about the viability of her candidacy as she struggled to gain ground against oyster farmer Graham Platner in the Democratic primary.

Her announcement shakes up a pivotal race that Democrats see as critical to their chances of gaining the majority in the U.S. Senate. Mills was recruited by Senate minority leader Chuck Schumer, D-N.Y. — who viewed the two-term governor as the best candidate to take on Republican Sen. Susan Collins in November — but she struggled to match or blunt Platner's momentum after he launched his campaign in August last year.