MOSCOW, June 20 (RIA Novosti) - The successor to incumbent Russian President Vladimir Putin remains at the top of the country's political agenda, Andrei Ryabov, scholar-in-residence at the Carnegie Moscow Center, wrote in today's issue of the Gazeta daily.

Defense Minister Sergei Ivanov's chances of winning the presidency seem to have fallen after an attack on his department launched by prosecutors over crime in the military and the involvement of Ivanov's son in a fatal traffic accident.

The succession issue has been put on the table again after the government's appointment of Vladimir Yakunin, known as a close Putin ally, as the head of the Russian Railways, the national railway operator. A Putin loyalist, Yakunin was seen a top candidate for the presidential chief of staff in October 2003, and is even seen as a replacement for Mikhail Fradkov, the current prime minister, if Putin ever decides to dismiss him.

However, the 2008 presidential election is still a long way ahead. Moreover, recent security failures - the bombing of a Grozny-Moscow passenger train and the derailing of a fuel oil train in the Tver region, both within 200 miles from the capital - suggest Yakunin will have little time for politics, at least in the short term.

Experts' interest in who will be the successor is obviously genuine. After Putin twice vowed to step down in 2008, Russia's political elite, most of whom are the president's allies from his home city of St. Petersburg, seemed be unprepared for an open battle or power. This is why they are now seeking an institutional solution that would see Putin remain the national leader, Ryabov wrote.

Some people suggest changing the current president-government division of powers in favor of the government without amending the constitution. For example, a member of the Liberal Democratic Party, Alexei Mitrofanov, has proposed that parliament elect the president, which is the model used in a parliamentary republic.

Other people propose amending the constitution via a referendum to preserve the current system of power, or establishing a Union State with Belarus to keep the key figures of Russian politics in power but in a new capacity.