ST. PAUL — The race for Minnesota governor in 2018 got off to an early start Thursday as a top Minnesota House Democrat launched her campaign, the first candidate from either party to make it official.

Rep. Erin Murphy filed for the office after more than a year of publicly considering a run to replace Democratic Gov. Mark Dayton. Murphy is a Democrat from St. Paul who rose through the ranks during her six terms at the Legislature, eventually serving as House majority leader in 2013 and 2014 before Democrats lost control of the House.

Murphy may have been the first to set up a gubernatorial campaign, but she won’t be the last. There is a long list of possible candidates from both parties who are considering a run to replace Dayton, who has vowed he’ll leave office at the end of his second term. In 2010, when Dayton won the open seat, more than 20 candidates were in the running — including 10 on the Democratic side alone.

The early campaign formation allows Murphy to start raising money for a costly endorsement battle and, she hopes, a general election. She said she doesn’t plan to run in a primary if the party endorses a different candidate.

A nurse deeply involved in long-running debates about Minnesota’s health care, Murphy said improving health care access and affordability are at the heart of her campaign along with tackling the school achievement gap and expanding early education options.

“I’ve seen way too much short-term political thinking and not nearly enough discussion about needs of the future,” Murphy said in a phone interview Thursday. “There’s a lot of work to do.”

Republicans and allied political groups immediately pounced on Murphy’s announcement, digging up Murphy’s old Twitter posts that celebrated the passage of Minnesota’s health insurance exchange and tied her to next year’s double-digit premium increases. Murphy voted to create MNsure, Minnesota’s way of complying with the Affordable Care Act.

“Murphy is dangerously out of touch and we look forward to highlighting her record,” said John Rouleau, a spokesman for the Republican-aligned Minnesota Jobs Coalition.