WATCH: Trump marks 100 days in office

President Donald Trump is marking his 100th day in office by talking tough on trade.

The White House says the president will sign an executive order Saturday that will direct his Commerce Department and the U.S. trade representative to perform a comprehensive study of the nation's trade agreements.

The aim is to determine whether America is being treated fairly by its trading partners and the 164-nation World Trade Organization.

The venue for the signing of the executive order is a shovel factory in Pennsylvania's Cumberland County.

In the evening, the president will appear at a rally in Harrisburg to cap the occasion of his first 100 days in office.

He won Pennsylvania, a state that is considered crucial to winning the election, after it was held by Democrats for almost 30 years.

A recent Gallup poll shows Trump's approval rating at 43 %

And a new CNN/ORC poll finds  44% say they approve of Trump's handling of the presidency, 54% disapprove.

That's about the same as in each of the two previous CNN/ORC polls taken after his inauguration.

That 44% marker puts Trump last among approval ratings for newly-elected presidents at the 100-day point since modern polling began, a trendline that runs back to Dwight Eisenhower. Trump is last by a significant margin, trailing Bill Clinton's previous low by 11 points.

With files from Heather Goode