The chips are on the table two months before the midterm elections and it is becoming increasingly clear where Sen. Mitch McConnell, R-Ky., thinks Republicans are most competitive in the 2018 midterm elections.

The Senate Leadership Fund, a McConnell-aligned super PAC, opened its first serious salvo Tuesday dropping $6.4 million on television advertising and sending incumbent Democrats scrambling. This is just the beginning in the war for control of the upper chamber. As USA Today was first to report, the super PAC has stockpiled $60 million for the midterm elections.

The money gives a good idea of where Republicans will be going on offense. At the same time, it demonstrates which candidates convinced McConnell they were worth the return on investment.

Missouri

While Republican challenger Josh Hawley got off to a slow start, incumbent Sen. Claire McCaskill, D-Mo., remains vulnerable. McCaskill owes her seat less to her political acumen and more to the political gaffe of her opponent in 2012, then Rep. Todd Akin. The two had been neck-and-neck until Akin answered a question about abortion by saying that “legitimate rape” seldom resulted in pregnancy. McCaskill wiped the floor with Akin after that remark.

Hawley won’t make an idiotic comment and this race will remain competitive so long as he can unify a Republican party still reeling from the resignation of disgraced former Gov. Eric Greitens.

RCP Average: Hawley +0.6
Trump 2016 Victory: +18.5
McConnell Bets: $1.8 million

Indiana

Businessman-turned-politician Mike Braun upended the Republican Senate primary in May. He let Reps. Luke Messer and Todd Rokita bash each other over the head, then glided to the nomination. Braun hasn’t yet had the same success against incumbent Sen. Joe Donnelly, D-Ind. But the challenger has pressured Donnelly on everything from abortion to outsourcing to the Supreme Court.

Donnelly faces an uphill battle, but he understands the centrist geography. He has maintained the lead throughout August so far. McConnell’s investment here may possibly be the biggest Republican bet of the midterm elections.

RCP Average: Donnelly +5.7
Trump 2016 Victory: +19
McConnell Bets: $1.4 million

West Virginia

Sen. Joe Manchin is the most vulnerable incumbent on the map right now. After endorsing Barack Obama and Hillary Clinton in their presidential elections, the West Virginia Democrat seems complicit in the War on Coal.

State Attorney General Patrick Morrisey, on the other hand, is the conservative champion of coal country. He effectively defeated the Obama administration’s Clean Power Plan at the Supreme Court which would’ve destroyed that industry and, in the process, he catapulted himself to the Republican Senate nomination. Trump started an electoral avalanche in the state and Morrisey has similar momentum two years later.

McConnell is dropping serious money but not too much. With the Trump family’s many visits to the Mountain State, McConnell may think Morrisey can do more with less.

RCP Average: Manchin +8.4
Trump 2016 Victory: +42.2
McConnell Bets: $800,000

North Dakota

Sen. Heidi Heitkamp is holding on up north against Republican challenger Rep. Kevin Cramer. She has developed a reputation as more of an old westerner than a partisan and she has kept the race competitive. But her opponent, who like her represents the entire state, has decent name recognition and a slim lead. McConnell seems modest with his initial bet on North Dakota even though Trump cleaned up in the state. But it's not an expensive place to advertise With two months to go, that could always change.

RCP Average: Cramer +0.5
Trump 2016 Victory: +36.3
McConnell Bets: $350,000