April 30 (UPI) -- Maine Gov. Janet Mills dropped out of the race for Senate Thursday, saying she just couldn't raise enough money to fight off a strong challenger.

"While I have the drive and passion, commitment and experience, and above all else -- the fight -- to continue on, I very simply do not have the one thing that political campaigns unfortunately require today: the financial resources," Mills said in a statement. "That is why today I have made the incredibly difficult decision to suspend my campaign for the United States Senate."

Mills, 78, a Democrat, was running to unseat Sen. Susan Collins, R-Maine, 73, but first she had to face newcomer Graham Platner. Platner, 41, is an oyster farmer who has the endorsement of Sen. Bernie Sanders, I-Vt.

Platner will likely face Collins in November. He has led Mills in the polls and has drawn large crowds for his events around the state.

Mills ran ads against Platner showing old Reddit comments that Platner had made. She also brought up a tattoo that Platner had that appeared to be a Nazi symbol. He has since removed the comments.