WARSAW, Poland (AP) — Poland won't back former Prime Minister Donald Tusk for a second term as European Council head, the head of the conservative ruling party said Tuesday.

Jaroslaw Kaczynski said in comments published on the "Polska The Times" website that Tusk might face charges in Poland, and the European Union should be aware of that. He said that wouldn't bar Tusk from winning a second term in an EU vote next year because Poland has no veto power.

"I can imagine that the Polish government will not back Donald Tusk for a second term in the European Council," Kaczynski said. "Tusk is a great problem."

The issue is linked to the 2010 death of President Lech Kaczynski and 95 other public figures in a plane crash in Russia.

Jaroslaw Kaczynski, the late president's twin brother, blames Tusk, Poland's prime minister at the time, with neglecting the president's security amid a simmering political conflict between them. Tusk denies any responsibility and says he is ready to testify as a witness in the investigation.

Under the 11-month rule of Kaczynski's Law and Justice party, a special parliamentary aviation commission and prosecutors have opened new investigations into the crash, pushing assassination and explosion theories. It isn't clear when their work will be concluded, but they haven't come up with any significant new evidence so far.

Kaczynski said the probes may result in charges being filed against Tusk.

Prime Minister Beat Szydlo also said that she "can imagine" that her Cabinet won't back Tusk in Brussels. That could weaken his position should he win a second term.

Polish and Russian commissions have blamed the crash on human error in bad visibility conditions. The Russian commission additionally blamed pressure from the passengers on the crew to land, despite the risk.