KIEV, June 29 – Vitaliy Klichko, an opposition leader who may have the best chance of defeating President Viktor Yanukovych at the next presidential election, vowed to disrupt any attempts by the government to amend Ukraine's constitution through a plebiscite.

He issued a statement amid speculation the Yanukovych administration may be considering amending the constitution to make it easier for the incumbent to win re-election in March 2015.

The speculation rose recently after Justice Minister Oleksandr Larvynovych defended the idea that the constitution can be amended via a referendum and without involving Parliament.

“Today the government, which understands that it will never win a fair election, is going to once again re-write the constitution to suit itself via the so-called referendum,” Klichko said in the statement. “I want to disappoint authors of this scenario: you won’t be able to do it.”

“We will not let the authorities amend the constitution through the referendum and will not allow any changes to the law without Parliament,” Klichko said.

The statement underscores a widening gap between Klichko and Yanukovych, potentially setting stage for a major political battle within the next 12 months.

Earlier in June Klichko refused to join Yanukovych for a crisis meeting at the presidential administration, and insisted that the president must come to Parliament to deliver his State of the Nation address.

The developments come as Klichko has been gaining in popular support among people in Ukraine and for the first time ever has scored the best rating among other politicians in Ukraine.

Klichko scored 16% support among respondents in May compared with Yanukovych’s 14% with other figures trailing behind, according to latest opinion poll released in June. The numbers suggest that Klichko may be the best suited to defeat Yanukovych in the election, analysts said.

Although no plans have been officially announced concerning the constitutional amendments, opposition groups suspect that Yanukovych may seek to amend the constitution to allow election of the next president in Parliament, scrapping a popular vote.

Other potential changes may include election of the next president in a one-round vote that could potentially benefit Yanukovych, analysts said.

Yanukovych last year signed into law a legislation that regulates the use of referendums in Ukraine and that opens way for potentially amending the constitution.

The issue is highly sensitive as current legislation calls for any amendments to be approved by Parliament only and the approval requires 300 votes in the 450-seat legislature. The current legislation makes it very hard to approve the amendments in Parliament as opposition groups can easily block such an approval. (tl/ez)