President Donald Trump adjusts his jacket during a tour of Apple's Mac Pro manufacturing plant in Austin, Texas, November 20, 2019.

Ahead of a historic House vote that's expected to impeach President Donald Trump, a new CNBC All-America Economic Survey finds the nation evenly divided on the question, but about 1 in 5 Americans are either open to changing their mind or are unsure.

The poll of 800 Americans nationwide found that 45% disapprove of Congress impeaching Trump and 44% approve, little changed from September. Of those who have an opinion, 10% say they are open to changing their minds and 11% are unsure.

The poll, conducted Dec. 10-13, has a margin of error of plus or minus 3.5 percentage points.

The poll shows a massive partisan split, with 78% Democratic support for impeachment and 83% Republican opposition. Independents disapprove of impeachment by 46% to 41%.