WARSAW—Poland's newly installed right-leaning ruling party on Thursday took steps to replace judges elected to the country's top court with its own nominees, as it seeks to clear legal hurdles to its agenda of sweeping change.

A right-leaning majority in the Sejm, Poland's lower house of parliament, passed a number of resolutions declaring recent appointments of highest-court judges invalid. The ruling Law and Justice party will now be able to push through the election of new judges to the Constitutional Court whose rulings on legislation are final.

Poland's new ruling party came to power in an election in October after promising deep changes to the way Poland is governed, including creating new administrative regions, reshuffling the judiciary and amending the constitution.

To make sure those changes stand, Law and Justice leader Jaroslaw Kaczynski said on Wednesday the party needed to change the highest court first because, in his view, it had become a nest filled with his political opponents who would try to complicate the government's work.

The moves seek to have a similar effect to action a few years back by Hungary's heavy-handed leader Viktor Orban who limited the Hungarian constitutional court's ability to rule on a range of government efforts. Poland's Mr. Kaczynski has frequently cited Mr. Orban's style of governance as a possible model, a system where the ruling party's firm grip on power allows it to override domestic opponents' objections while ignoring criticism from abroad.

The opposition in Poland as well as the chairman of the Constitutional Court cried foul after Mr. Kaczynski's party voted to reverse the appointments made during the previous parliament's final months.

"Law and Justice is over. Today it's Lawlessness and Injustice," said Ewa Kopacz, former prime minister.

Yet it is Ms. Kopacz's move that the Polish new ruling party says it's trying to rectify. It was under her that parliament in the previous term nominated the new judges when it was becoming increasingly clear Ms. Kopacz's Civic Platform party would lose power. The party quickly appointed five new judges, in two cases preempting appointments that were to be made by the new parliament inaugurated this month.

After taking office this year, President Andrzej Duda refused to swear in the new judges, which gave Law and Justice time to cancel their nominations before they started work in the court.

Since its appointment last week, Poland's new government has attempted to reverse course on a number of issues. The defense minister said on Wednesday Poland wouldn't necessarily buy the Patriot missile-defense system from Raytheon Co., which was the previous government's plan as part of a $40 billion effort to modernize Poland's armed forces. Similarly, the new government said it would review a tentative deal to buy military helicopters from Airbus Group NV.

The new government in Warsaw is also trying to prompt European Union partners to revisit the issue of migrant resettlement across the bloc. In a more symbolic gesture, EU flags disappeared from government press conferences this week, although President Duda has used them during public events, displayed alongside the Polish national flag.

Write to Martin M. Sobczyk at martin.sobczyk@wsj.com

Subscribe to WSJ: http://online.wsj.com?mod=djnwires

(END) Dow Jones Newswires

November 26, 2015 10:15 ET (15:15 GMT)