Polish prime minister Donald Tusk said on Saturday that he aimed to strip the country's president of his veto powers in a constitutional revamp designed to end institutional conflicts that have blocked key reforms.     

President Lech Kaczynski, Tusk's conservative arch rival, has vetoed a number of government bills, including media, health and pensions reforms, citing their impact on ordinary workers.                                           

Kaczynski and his twin brother Jaroslaw, who heads the main opposition, eurosceptic Law and Justice party (PiS), have also hampered Tusk's efforts to introduce the euro in Poland.

"The president should not have veto power. People make their decision in elections and then state institutions should not be in conflict," Tusk told a news conference marking the second anniversary of his centre-right, pro-market reform government. 

"Let us change some provisions so we can have fewer conflicts and more cooperation. We propose changes to the constitution so that the centre of power lies with the government... The presidential veto brings more harm than good." 

Under his proposed changes, which Tusk said could come into effect in time for a presidential election due next October, the president would become a largely ceremonial head of state chosen by the parliament, not directly by voters as at present. "Poles should know who rules... We can create a political system that is more efficient and comprehensible."                                           

Tusk recently blamed Kaczynski for an expected rise in the government's budget deficit and public debt next year because of the president's stated readiness to veto spending cuts.

Tusk and Kaczynski have also tussled in the past over who should represent Poland at international meetings such as European Union summits. Both men usually attend the gatherings.                                           

Tusk, Poland's most popular politician, said parliament could approve a bill on constitutional reform by the spring and said he did not rule out holding a referendum on the changes.

An aide to president Kaczynski, Pawel Wypych, swiftly criticised Tusk's proposals as an attempted power grab by the ruling party and said it was unrealistic to try to overhaul the constitution in such a short period of time.                                           

Enacting the reform is theoretically possible but Tusk would require the support of the leftist opposition and also of deputies who have defected from PiS to attain the veto-proof two-thirds majority needed to change the constitution.                                           

PiS would be likely to oppose the constitutional bill. Tusk has been widely expected to challenge Kaczynski for the presidency in next year's election but analysts say he would probably want to stay on as prime minister if his constitutional bill succeeds and the president becomes just a figurehead.