(CNN) Oil and gas companies give more in campaign contributions to members of Congress with voting records against the environment, according to a new study.

The study found the oil and gas industry is more likely to invest in the campaigns of legislators who receive a lower score from environmental groups that track their voting records.

The research was published Monday in the journal Proceedings of the National Academy of Sciences

Researchers looked at spending in consecutive election cycles from 1990 to 2018 to study the relationship between the voting records of members of Congress on environmental policies and campaign contributions from the oil and gas industry.

Researchers gathered data on campaign contributions from the Center for Responsive Politics (CRP) and matched it with congressional voting records from the League of Conservation Voters (LCV).

Influence vs investment

The study points to two theories: One is known as the "influence hypothesis," in which companies contribute to a campaign in hopes of influencing a legislator's vote.

The other theory, known as "investment hypothesis," explains that companies do not donate money to persuade a legislator; rather, companies spend on politicians already voting in line with the company's policy goals.

Researchers found that, on average, a lower score from the LCV in one election predicted at least $1,700 in campaign contributions from oil and gas companies to a member of Congress in the next cycle, meaning these companies invest in legislators that already vote against environmental legislation.

An even stronger result was observed in the 2016 election cycle. For every additional 10% of votes against the environment in 2014, the member of Congress would get an additional $5,400 in campaign donations, according to the study.

"There's little evidence that oil and gas companies use campaign contributions to influence the voting behavior of members of Congress," Matthew Goldberg, a post-doctoral associate from the Yale Program on Climate Change Communication and study co-author, told CNN. "Rather, they invest in legislators that have a proven anti-environment voting record."

Goldberg said one of the limitations of the study is that it didn't examine other ways oil and gas companies influence the views of members of Congress, including access to meetings or lobbying efforts.

"When researchers measure campaign contributions and legislators' voting record at the same time point, it is difficult to know which came first, the contributions or the voting behavior," Goldberg said. "Because our study examines these variables across many election cycles, we get a better idea of the order of events."

Oil and gas companies contributed more than $84 million to congressional campaigns in 2018 alone, according to the study. That is more than double the amount that industry contributed since the 2010 Citizens United Supreme Court decision that allowed unlimited election spending by corporations and labor unions through super PACs.