The outcome of the presidential election is expected to have a dramatic impact on U.S. energy and environmental policy, with Vice President Harris and former President Trump offering starkly different visions on the issue.

But the outcomes of congressional elections will also be crucial, particularly with razor-thin margins in the House and Senate raising the possibility that the winner will be the first president to enter office without a trifecta since George H.W. Bush.

Here are five key races to watch next week and how they could affect the next administration’s energy and environment agenda.

Montana’s Senate race

The candidates: Sen. Jon Tester (D) and businessman Tim Sheehy (R).

Why it matters: Tester, like retiring Sen. Joe Manchin (D-W.Va.), is a Democrat from a red state all but guaranteed to be won by Trump for a third time, and like Manchin, has never sought reelection with Trump at the top of the ballot.

With Manchin not seeking reelection and Gov. Jim Justice (R) an overwhelming favorite to win the open seat, Tester is considered the weakest incumbent Senate Democrat: The Hill/Decision Desk's polling average currently shows him trailing Sheehy by 6 points.

The Montana Democrat has not butted heads on energy and environment with the Biden administration as often as Manchin, but he has joined Republicans in voting for Congressional Review Act (CRA) resolutions to overturn Biden rules on environmental and sustainable governance rules and highway greenhouse gas emissions.

Unless Democrats pick up a seat, a Tester loss would give Republicans a majority of at least one seat in the chamber. And while Tester has broken with the White House on CRA votes, he has also supported energy and environment-related measures and nominees promoted by the Biden administration, including the sweeping Inflation Reduction Act (IRA). Sheehy, meanwhile, would almost certainly oppose any environmental legislation backed by a Harris presidency.

Michigan’s Senate race

The candidates:........

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