Parliament recently approved a bill to give MPs the power to select members of the body that nominates judges.

Opponents say the move would erode the independence of the judiciary.

In a televised address, Mr Duda proposed that nominations to the body would need more than a simple majority in parliament.

It would mean the governing conservative and populist Law and Justice Party (PiS) would need the support of at least one other party to ensure its nominees are approved.

President Duda said that if the lower house did not approve his change to the bill, he would not sign a separate controversial bill on changes to the supreme court.

That bill would mean that all sitting supreme court judges would lose their posts and the National Council of the Judiciary would appoint new judges.

Mr Duda is a former PiS member who was nominated for president by party leader Jaroslaw Kaczynski.

However, relations between the two have not been good for some time, the BBC's Adam Easton in Warsaw says.

If President Duda had signed the bill as it stood, the Law and Justice party would be able to appoint members to the body that selects judges.

Opposition parties and human rights groups have said the reform erodes the independence of the judiciary because currently the council is selected by professional legal associations.

The government says the reforms are needed because the judiciary is corrupt and serves only the elite.

On Tuesday, several thousand people holding candles gathered outside the presidential palace to protest against the reforms.

Parliament has been cordoned off since Sunday when thousands staged demonstrations in Warsaw and other cities.

(Published by BBC - July 18, 2017)