Delivering an outdoor speech to a crowd of hundreds at an oil refinery Wednesday, Trump called for the state's governor and congressional delegation to join him on stage, including Sen. Heidi Heitkamp, the only statewide elected Democrat in heavily Republican North Dakota.
"Everybody's saying: What's she doing up here?" Trump said of the first-term senator, adding: "I hope we'll have your support" and calling her "a good woman."
Heitkamp, up for re-election next year, flew in with Trump aboard Air Force One as he sought to frame the tax overhaul as a "once-in-a-generation" opportunity to cut taxes and simplify the tax code.
But while Trump's White House is talking hopefully about bipartisanship, GOP leaders in Congress have made clear they're pursuing a go-it-alone strategy on taxes that has shut Democrats out of the negotiations.
Trump used the event to sell his plan, but its details are still to be determined. He said he'd be getting into "great detail" on the plan in the next two weeks. Overall, it calls for a major simplification of the tax code and lowering personal rates, especially for the middle class, by raising the standard deduction, among other changes, and lowering business taxes to about 15 percent.
"It's your money, not the government's money," Trump said.
Trump emphasized that the last time Congress passed a major tax overhaul, under President Ronald Reagan in 1986, Democrats signed on.
"Both of the Reagan tax cuts were passed by a Democratic majority in the House, a Democratic speaker, and a vast majority of Democrats in the Senate, including a Democratic senator from the great state of North Dakota," Trump said. "So it can happen. Are you listening Heidi?"
"If Democrats 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," he said.
Trump traveled to North Dakota after a meeting with congressional leaders at the White House in which the president sided with Democrats on a deal to fund the government and raise the federal borrowing limit for three months, all aimed at expediting money for Harvey relief.
Marc Short, Trump's top legislative adviser, told reporters aboard Air Force One that "helping to clear the decks in September enables us to focus on tax reform for the American people. We need to get the economy growing again and that's what the president focused on."
Trump has sought to pressure Democrats to back the tax plan, a key priority after his push to overhaul the health care system failed.
During his first tax speech last week in Missouri, the state's Democratic Sen. Claire McCaskill stayed away. In his remarks there, Trump urged people to vote her out of office if she did not support lowering taxes.
Heitkamp is expected to face a tough challenge in next year's midterm elections. While she narrowly won the state in 2012, she is personally popular and has been careful to stake out policy positions that don't stray too far from the state's right-leaning electorate.
Heitkamp has not said she supports Trump's plan, only that the small business owners, energy industry workers, farmers and parents in her state are eager for changes to a tax code they believe is broken.
She said after Trump's visit that she was encouraged by his commitment to promoting American workers as key to any tax policy.
"But, as North Dakota's former Tax Commissioner, I know the devil is in the details of any reform plan as tax codes are complex, and we need to know what those details are," Heitkamp said in a written statement.
Trump was in friendly territory: He won North Dakota by 36 points last year and has championed policies that benefit its energy sector. Also joining the president were Republican Sen. John Hoeven and Republican Rep. Kevin Cramer, weighing a bid to challenge Heitkamp.
At one point, the president asked his daughter and senior adviser, Ivanka Trump, to come on stage and address the crowd. She thanked North Dakotans for their past support, noting, "you treated us very, very well in November."
Thomas reported from Washington. Associated Press writers Catherine Lucey and Josh Boak in Washington also contributed to this report.