US stock markets broke more records on Thursday as the Senate got closer to voting on a plan that would see corporate taxes slashed and billions of dollars of tax breaks handed to America's wealthiest individuals.

The Dow Jones Industrial Average rose 115 points to open above 24,000 for the first time ever on Thursday morning with Goldman Sachs the biggest gainer on the 30-stock index.

The S&P 500 reached an all-time high at the open, gaining 0.4 per cent, with financial shares leading the charge. The Nasdaq index rose 0.3 per cent after a 2 per cent decline on Wednesday.

Under the proposed Senate bill the corporate tax rate would be cut from 35 per cent to 20 per cent, and the individual tax code would be overhauled and simplified.

The Senate is expected to vote on Thursday following 20 hours of debate and a series of amendment votes earlier this week.

President Donald Trump has sold the bill as a win for middle-class families but multiple Republicans had expressed concerns about the legislation and its effects. However many of those sceptics have this week made comments suggesting they may vote ‘yes’.

If the upper chamber's bill passes, the House and Senate would have to work on a new bill to send to Mr Trump.

Independent experts say that the plan would explode the US government deficit.