LAS VEGAS (KLAS) — Nevada Democratic Sen. Jacky Rosen is pushing for the federal government to investigate how big oil companies are merging and reducing competition.

In a letter to the Federal Trade Commission, Rosen and 22 other Senate Democrats asked for a closer look at two planned mergers: ExxonMobil’s acquisition of Pioneer Natural Resources for $60 billion and Chevon’s purchase of Hess Corporation for $53 billion, her office said.

Less competition negatively affects consumers and drives up prices, Rosen said, adding she and her colleagues in the U.S. Senate can try to hold companies accountable.

“By allowing Exxon and Chevron to further integrate their extensive operations into important oil-and-gas fields, these deals are likely to harm competition, risking increased consumer prices and reduced output throughout the United States,” the letter said.

The U.S. average for a gallon of regular was $3.25 as of Wednesday, according to AAA. The average in Nevada was almost $1 higher at $4.17 – about 50 cents lower than this time last year and the fourth highest average after California, Hawaii and Washington State.

Amid record high gas prices last year, Chevon, ConocoPhillips, Exxon and Shell all reported record profits with more than $1 trillion in sales, CBS News reported.

“What really can you and your colleagues do?” 8 News Now Investigator asked Rosen on Wednesday.

“They have a responsibility to the consumer, and we can’t allow them to continue to reduce competition so they can continue to increase price,” Rosen said. “Price gouging is never right. They are making record profits.”

More than 2,600 oil companies merged in the 1990s, leading to higher prices, Rosen’s office said. By 2001, just nine major U.S. oil companies were in operation, leading to reduced competition.

Earlier this year, Nevada Democratic Sen. Catherine Cortez Masto reintroduced a bill to investigate if large oil companies took advantage of consumers as gasoline prices skyrocketed last year.

Cortez Masto first proposed The Fair and Transparent Gas Prices Act during the last Congress. If the bill were to become law, the government would give the Federal Trade Commission specific tools to look into possible price gouging.

Last year, both senators sponsored a bill to temporarily suspend the federal gas tax. Suspending the tax would have no impact on Nevadans as a state law automatically raises the state tax to offset any drop in the federal one.