BILLINGS, Mont. (AP) — Montana Republican Gov. Greg Gianforte reported more than $23 million in income over four years ending in 2022, as the former technology executive who is seeking reelection to a second term continues to rake in money from investments, according to tax records released by his campaign.

Democrat Ryan Busse, a former firearms industry executive, is challenging Gianforte in November.

Gianforte spent more than $6 million of his own money on a failed bid for governor in 2016. After getting elected to Congress in a 2017 special election, he ran for governor again four years ago and spent more than $7.5 million defeating Democrat Mike Cooney by a wide margin, according to campaign finance reports.

So far this election cycle, he has contributed roughly $47,000 to his campaign, the reports show.

Most of Gianforte’s income since 2019 came from profits on investments, his tax returns indicate. He is paid about $120,000 a year for being governor.

Spokesperson Anna Marian Block said Gianforte was keeping a “commitment to transparency” with Montana residents by releasing his returns.

Since 2005 Gianforte has reported income of more than $265 million, according to previous disclosures. The bulk of that money came after Oracle Corp. bought Gianforte’s Bozeman-based company, RightNow Technologies, for $1.8 billion.

Democrats and Gianforte's Republican primary opponents sought unsuccessfully in 2020 to turn Gianforte’s huge wealth into a liability, saying he wanted to buy the election.

Busse’s campaign declined to release his tax returns.