U.S. Senate candidate Graham Platner is raising — and spending — more money than Sen. Susan Collins in the heated race for the incumbent senator’s seat.

The Democratic political newcomer has raised $16.3 million this election cycle compared to Collins’ $15.1 million, according to federal campaign finance reports that were due Thursday. She has spent $7 million, while Platner has spent twice that at $14.1 million.

In the latest reporting period, which covered April 1 to May 20, Collins raised $1.7 million and spent about $2 million. Platner raised $4.4 million and spent $4.9 million.

Collins finished the period with close to $10 million in cash on hand, including funds leftover from her last campaign, while Platner had just $2.2 million in cash on hand.

The numbers preview what is likely to become an even more costly election as November draws closer. They also reflect the toll of the contentious Democratic primary Platner was in with Gov. Janet Mills up until late April, when Mills announced in a surprise move that she was dropping out of the race. Collins, seeking a sixth term, is not facing a Republican primary challenger.

Mills cited a lack of cash in her decision to withdraw, and the latest reports show she was trailing Platner badly in fundraising. The governor, who got in the race in October, two months after Platner did, raised just under $6 million total, compared to his $16 million.

In the latest fundraising period, she collected just under $500,000. Mills announced April 30 that she was dropping out, about halfway through the period.

Mills’ decision means Platner has almost certainly secured victory in the June 9 Democratic primary, though he still faces a challenge from long-shot candidate David Costello, who served in state government in Maine and Maryland and also worked in U.S. foreign aid.

Costello has raised around $150,000, including a loan of $110,000 to his own campaign, and has $42,000 in cash on hand.

Spending by the candidates is just a fraction of the money pouring into the Senate race. When spending by outside groups is accounted for, more than $142 million has already been spent on the race, according to advertising tracker AdImpact.

Collins has an advantage there, with total Republican-aligned spending on the race coming in at $99 million so far, compared to $44 million spent by Platner and Democrat-aligned groups, according to AdImpact.

RACE FOR 2ND DISTRICT SEAT

The Senate race is not the only highly anticipated federal election in Maine this year.

In the 2nd Congressional District, four Democrats are vying to take on former Republican Gov. Paul LePage for the seat currently held by U.S. Rep. Jared Golden, a Democrat who announced last year he wouldn’t seek reelection to a fifth term.

State auditor Matt Dunlap raised nearly $304,000 since April 1 and ended the fundraising period with about $93,500 on hand.

State Sen. Joe Baldacci, D-Bangor, raised about $213,000 and had $128,000 on hand, with House Minority Leader Hakeem Jeffries, D-New York, giving Baldacci $14,000 between his campaign and leadership PAC, among other contributors.

Jordan Wood, a former congressional aide, continued his pattern — since switching from the Senate race to the House race — of burning through cash, raising $573,000, including a loan of $150,000 from himself, and spending about $847,000 from April 1 through May 20. He has about $423,000 left on hand.

Graduate student and social worker Paige Loud has been behind the three other Democratic candidates in polling and fundraising and took in about $30,500 through May 20, with her campaign having about $2,800 on hand.

LePage, who has no primary to worry about, raised nearly $74,000 and has about $1.2 million on hand. He has continued in the past week to receive contributions from Mainers and from various out-of-state individuals and Republican-aligned political action committees.

Those contributions include $3,000 from the Florida First PAC that is tied to a right-wing Florida gubernatorial candidate, James Fishback, who has courted controversy lately; and $2,000 from U.S. House candidate Jace Yarbrough of Texas, who has staked out various extremist positions and called for reinstating race-based immigration quotas.

Staff Writer Billy Kobin contributed to this story.