President Trump will have Democratic company for his trip to North Dakota to talk taxes Wednesday.

Heidi Heitkamp, the state's Democratic senator, will travel with Trump aboard Air Force One to Bismarck, the White House told reporters Tuesday. Trump is headed to the Mandan facility of the Andeavor Corporation, an oil refiner, to give a speech on tax reform.

Heitkamp will be the first Democrat to join Trump as he tours the country to push for Congress to pass tax legislation. North Dakota's Sen. John Hoeven and Rep. Kevin Cramer, both Republicans, are also set to accompany the president.

A White House official said that he did not expect any sort of endorsement from Heitkamp at Wednesday's event, although he added that the administration is "optimistic" that Republicans will ultimately pick up Democratic support for changes to the tax code. For now, there is not yet legislation, only a broad set of principles.

Nevertheless, most Senate Democrats have ruled out support based on that outline. Heitkamp's office referred to a conciliatory but carefully worded statement the senator made last week when asked for comment. Republicans aim to pass tax legislation using a special legislative procedure that requires only a simple majority. There are 52 Republicans in the upper chamber.

Trump flew to Springfield, Mo., last week to talk taxes, putting pressure on another Democrat who could be vulnerable in the 2018 elections, Claire McCaskill. White House officials said that Trump plans to travel regularly throughout the country, almost weekly, to try to gain votes for tax reform.

A White House official said that Trump plans to call out Democrats in Wednesday's speech, saying that "if Democrats continue their obstruction, if they don't want to bring back your jobs, raise your pay, and help America win, voters should deliver a clear message: Do your job to deliver for America, or find a new job."