Susan Collins, left, and Sara Gideon Credit: Patrick Semansky and Robert F. Bukaty / AP

The vast majority of campaign cash flowing into Maine’s U.S. Senate race is from outside of Maine, though House Speaker Sara Gideon, a Democrat, has raised more from in-state donors than Sen. Susan Collins in a race that has become a national focus for both parties.

Both Gideon and Collins have set fundraising records in the highly watched contest that also includes two independents, teacher and former Green party candidate Lisa Savage of Solon and pro-Trump conservative Max Linn, a retired financial planner and former Florida gadfly candidate from Bar Harbor. The race will use ranked-choice voting.

Out-of-state money has been a line of attack from both sides of the aisle. While it is taking an outsized role in this election, it is in line with other heavily nationalized Senate races to date as Democrats look to take back the Senate, a mission that looked uphill a few months ago but looks more attainable now as the list of close-polling states has increased.

Democrats have been critical of Collins’ fundraising sources, linking the incumbent Republican to conservative groups such as the Federalist Society and the pharmaceutical industry. Collins has attacked Gideon’s connections to liberal groups, including those that organized a fundraising drive after Collins’ vote to confirm Supreme Court Justice Brett Kavanaugh in 2018.

Recently, the incumbent Republican’s campaign also attacked Gideon as having received the most money from out of state in Maine history. The claim is true, but the Freeport Democrat has also received the most in-state cash of any Senate candidate in Maine’s history and Collins raised a greater percentage of her money from out of state than Gideon.

The race has set fundraising records. Gideon has raised more than $23 million through June 30, the most recent date for which data are available, almost all of which has come from individual contributors. Collins has raised more than $16 million this cycle, with about $12.7 million coming from individuals and $3.8 million coming from PACs.

Using several different campaign finance reports, it is possible to parse out what share of individual contributions came from Maine residents and what share came from donors in other states. Campaigns are required to report the name and address of all contributors who give more than $200 to the Federal Election Commission, which regulates campaign finance.

Information about contributors who give less than $200 but give it through conduits, such as the Democratic platform ActBlue and Republicans’ WinRed, are also reported. Although not all small-dollar contributors give this way, a significant portion of them do, making it possible to account for about 95 percent of Gideon’s fundraising from individual donors and about 90 percent of Collins’ fundraising.

Gideon has raised at least $2.5 million from Maine residents, according to federal filings, accounting for about 12 percent of her fundraising from individuals where the donor’s residence is known. Collins raised at least $1 million from Maine residents, accounting for just shy of 9 percent of the fundraising where the donor’s residence is known.

Both the share and amount of out-of-state money flowing to both candidates exceeds that of previous Maine congressional races, a reflection of how the race has garnered national attention as part of the battle for a majority in the Senate.

In 2018, Sen. Angus King, I-Maine, received just over half of his money from Maine when the donor’s residence was known, according to the Center for Responsive Politics, a nonprofit that tracks campaign finance. When Collins ran for reelection in 2014 — a race she won with 68 percent of the vote — 31 percent of her fundraising from individuals came from Maine, though she only raised a total of $6.2 million that cycle, including both individual and PAC contributions.

However, Collins and Gideon’s fundraising is on par with candidates in other competitive Senate races this year. Among current senators facing re-election, Collins has raised the fifth-most from states other than the one she represents, according to the Center for Responsive Politics, trailing Senate Majority Leader Mitch McConnell, R-Kentucky, Sen. Martha McSally, R-Arizona, Sen. Lindsay Graham, R-South Carolina, and Sen. Doug Jones, D-Alabama.

Collins’ overall fundraising totals look similar to those of other Republican senators in major swing races. Compared to other longtime senators, she has received fewer contributions from the pharmaceutical industry. According to the Center for Responsive Politics, both Collins and Gideon get the plurality of their individual contributions from retirees, as is typical of candidates on both sides of the aisle.