PORTLAND, Maine (AP) — The costliest political race in Maine history didn't conclude on Election Day: Neither Republican Sen. Susan Collins nor Democratic Maine House Speaker Sara Gideon were able to declare victory.

Ballots were still being counted to determine a winner in the hard-fought contest, one of several that were crucial in determining whether Democrats take control of the Senate.

“We’re doing really well, but I know it’s not over until it’s over,” Collins told reporters late Tuesday in Bangor before calling it a night.

Gideon, for her part, did not appear before reporters at a Portland hotel but issued a statement saying she was grateful to her supporters.

“It’s clear this race will not be called tonight and we are prepared to see it through to the finish. Over the coming days, we will make sure that every Mainer has their voice heard in this election,” she said.

The Senate race was the most expensive in Maine’s history with Gideon raising nearly $70 million, more than double the $27 million that Collins raised. But that didn’t include so-called dark money. All told, more than $120 million was spent by both candidates and their allies on advertising.

With most but not all votes counted, Collins held a slim majority but it was too early for The Associated Press to declare a winner. There also were two independents, Lisa Savage and Max Linn, in the race.

Further complicating the calculus was Maine's ranked choice voting system. If no candidate wins a majority of first-place votes, then there would be additional tabulations, aided by computers, in which last-place candidates are eliminated and votes reallocated to ensure a majority winner.

The Senate race wasn't the only political contest in limbo in Maine.

The 2nd Congressional District clash between Democratic U.S. Rep. Jared Golden and Republican Dale Crafts was also too early to call.

In the presidential race, Democrat Joe Biden won at least three of four electoral votes by winning a majority of the statewide vote and a majority of the vote in the 1st Congressional District.

But it remained unclear whether President Donald Trump had eked out a majority in the more rural and conservative 2nd Congressional District to claim one electoral vote, as he did in 2016.