US President Donald Trump looks at a sample of the proposed new tax form at the White House in Washington, DC, on Nov. 2, 2017.

Over 400 millionaires and billionaires from the United States plan to send a letter to Congress this week petitioning on lawmakers not to cut their taxes — but to raise taxes on the wealthy, according to a Washington Post report.

Instead of calling for tax cuts for the rich, the letter urges lawmakers not to pass any tax bill that "further exacerbates inequality" and adds to national debt, the article said. The move comes at a time when inequality is at its peak since the 1920s and government debt levels are also high, the Post reported.

The letter was put together by liberal group Responsible Wealth. Most of its signatories come from California, New York and Massachusetts, states that voted for Democrat Hillary Clinton in last year's presidential race, according to the Washington Post.

The support of Republican representatives from California, New York and New Jersey is expected to be crucial for the GOP's tax reform efforts to see success, the Post reported.

Read the full story on the petition on the Washington Post.