President Donald Trump, facing doubts about the speed of his promised tax reform, said Thursday he will announce a plan in a few weeks.

In a meeting with U.S. airline executives, Trump spoke again on removing regulations for American businesses.

"Lowering the overall tax burden on American business is big league ... that's coming along very well. We're way ahead of schedule, I believe. And we're going to announce something I would say over the next two or three weeks that will be phenomenal in terms of tax," Trump said.

In a press briefing on Thursday, White House spokesman Sean Spicer told reporters that Trump realizes middle-class Americans need tax relief and that the U.S. needs "fundamental comprehensive tax reform."

The president also wants to create a tax plan that keeps jobs here, and incentivize companies to grow and come here, Spicer said.

Stocks and Treasury yields had jumped in the wake of Trump's Nov. 8 victory, amid the prospects for looser regulations in certain sectors, lower tax rates and fiscal stimulus.

However, investors appeared to be worried about delays after complications surrounding Republican attempts to repeal and replace Obamacare.