WASHINGTON (Reuters) – President Donald Trump will turn his signature populist rhetoric toward tax reform on Wednesday in a speech expected to tout tax cuts as a way to help workers and the middle class in an economy “rigged” against them, senior White House officials said.

With his domestic policy agenda stalled amid Republican infighting and his approval rating at just 35 percent, Trump will make his first presidential speech specifically on tax policy, an issue on he has been promising results for months.

Reiterating a 2016 campaign theme on a visit to Springfield, Missouri, Trump will say the U.S. economy is “rigged” to favor the privileged few and urge closing loopholes for the wealthy and special interests to help “Main Street.”

The officials, who asked not to be identified during a conference call with reporters, said those ideas would make for a “bipartisan” message, because the notion of a rigged economy cuts across the spectrum of U.S. political ideology.

The officials said the speech would be about “why” reforming the tax code was needed, not about “how” to reform it, which is the difficult part of fixing a 70,000-page set of laws and regulations that has not been overhauled since 1986.

Trump owes his November election victory partly to his ability to get working-class Americans to support a range of business policy positions, including his call for slashing the U.S. corporate tax rate to 15 percent from 35 percent.

That connection makes Trump “uniquely positioned as a politician to make the case for an overhaul of the business side of the code and to frame it as being good for the American worker,” said Rohit Kumar, a tax policy expert at accounting and consulting group PwC and a former senior Senate tax aide.

Tax reform was a major campaign promise for Trump and his Republican allies in Congress last year. But the effort has been hamstrung by repeated delays and political distractions since Trump took office in January.

The speech is unlikely to provide new details about a tax plan Trump’s aides and Republican leaders in Congress are trying to hammer out in closed-door meetings in Washington.

‘TOUCHSTONE’

With Republicans still reeling from their failed effort to dismantle the Affordable Care Act, popularly known as Obamacare, Trump’s remarks could bolster tax reform as a priority for Congress.

“It could be an excellent touchstone for lawmakers as they return after Labor Day, laying out a marker saying there’s an urgency for this to be among the first orders of business when we return,” said Representative Peter Roskam, Republican chairman of the House Ways and Means tax policy subcommittee.

Lawmakers will have other vital issues to handle when they return from vacation next week, including raising the federal debt ceiling and avoiding a government shutdown.

Some Republicans have complained that Trump’s public efforts are coming late in the legislative year and worry his speech on Wednesday could veer into issues that might overshadow tax reform, including U.S. race relations, North Korea and his differences with Republicans in Congress.

The White House said the speech would kick off a series of Trump appearances on tax reform. No details were provided.

Trump was also likely to use his speech to step up criticism of Missouri’s Democratic senator, Claire McCaskill, who faces a tough re-election bid next year in a state that went for Trump in 2016.

“Dem C.M. is opposed to big tax cuts,” Trump said earlier this week in a tweet aimed at McCaskill.