Libertarian billionaire Charles Koch is wading into the Kansas Senate race between Republican Rep. Roger Marshall and Democrat Barbara Bollier. Americans for Prosperity Action, a super PAC affiliated with Koch, is pouring money into Marshall's campaign with the hope of holding the seat of outgoing Republican Pat Roberts.

Koch has a powerful influence over Kansas politics, as his corporation, Koch Industries, is based in the largest city in the state, Wichita. According to Forbes, Koch has a net worth of $44.9 billion.

In January 2018, the Koch network pledged to spend up to $400 million to elect Republicans in the midterm elections. While Republicans held the Senate, Democrats regained the House and also won some critical state elections.

In early August, Marshall won the Republican primary for the seat against controversial anti-immigration candidate and former Secretary of State Kris Kobach.

Marshall, a 60-year-old physician, has served in the House since 2017.

Bollier, 62, is also a physician and member of the Kansas State Senate. She was a member of the Kansas House of Representatives from 2010 to 2017.

Bollier has touted her bipartisan support in the state, and has made healthcare and funding the postal service some of her top priorities. Bollier is a former moderate Republican who left the party due to differences with President Trump.

Marshall has pledged to help farmers and has emphasized his anti-abortion beliefs. He has criticized Bollier, claiming she is not moderate but an “extreme liberal.”

Koch may be making a stronger push for Marshall due to recent polls, which show a tight race in what was once considered a solidly red state. The left-leaning Public Policy Polling released a survey in early August that showed Marshall with a 1-point lead, 43% to 42%. A Survey USA poll from the same month showed Marshall with a 2-point lead over Bollier, 46% to 44%.

A loss in Kansas would be considered devastating for Republicans. In 2018, Democrat Laura Kelly defeated Kobach in a highly publicized gubernatorial race. Kelly received 48%, while Kobach received 43% and independent Greg Orman received 6.5%.

Democrats will need to win three to four seats to take control of the Senate in November, depending on whether Democratic nominee Joe Biden wins the White House. Other promising Senate races for Democrats include Arizona, North Carolina, Georgia, Montana, Iowa, Maine and South Carolina.