Moscow  - Vladimir Putin is swapping the presidency for the prime minister's post when he steps down Wednesday to leave room for his hand picked successor-elect, Dmitry Medvedev.

While the two have promised to share power, how the so-called power tandem will function is anybody's guess.

Putin is set to become Russia's most powerful prime minister ever, as head of the party that holds a majority in both houses and the country's most popular political figure.

Over his eight years at the helm, he has centralized power in the executive, and analysts are skeptical that Putin will relinquish this power to take the traditionally weak and thankless premiership without changes.

Whether Medvedev, who owes his ascension solely to Putin, will have the independence to exploit this powerful post also has observers puzzled.

They remark that an analysis purely based on the separation of powers provided in the constitution ignores the nepotistic ties inherent in Russian state politics.

The powers constitutionally assigned to each office:

PRESIDENT

- Head of State, office in Kremlin

- Acts as commander-in-chief of Russia's armed forces, including nuclear arsenal

- Sets strategy for foreign, domestic policies

- Guarantees constitution, protects citizens' rights

- Appoints, can summarily fire prime minister as well as other ministers with approval of Parliament

- Prime minister reports directly to president

- May chair cabinet meetings in place of prime minister

- All Russian security services report directly to president

- All federal ministers report to president

- Is supported by presidential administration in Kremlin

- Appoints, manages Russia's Security Council, which oversees country's defence policy

- Names central bank chief

- May impose state of emergency or military law as defender of Russia's sovereignty

PRIME MINISTER

- Head of cabinet, office in Moscow's White House

- Becomes acting president if president is not in a state to fulfill duties

- Carries out foreign policy, domestic policy

- Responsible for enacting presidential decrees, bills, international agreements

- Manages economic, fiscal policy

- Sets prices for gas, electricity, domestic transport

- In charge of social policy, labour policy, migration, family planning

- Civilian ministries report to prime minister (dpa)