FACTBOX: U.S. presidential candidates on Russia

(Reuters) - The U.S. presidential candidates have all questioned Russian President Vladimir Putin's selection of Dmitry Medvedev as his successor.

Here are some of their recent comments.

DEMOCRATIC SEN. HILLARY CLINTON:

At a Democratic debate on Tuesday, the New York senator stumbled over Medvedev's name while predicting he would not be an independent leader.

"Medvedev -- whatever," she finally said.

"I can tell you that he's a hand-picked successor, that he is someone who is obviously being installed by Putin, who Putin can control, who has very little independence.

"This is a clever but transparent way for Putin to hold on to power, and it raises serious issues about how we're going to deal with Russia going forward."

DEMOCRATIC SEN. BARACK OBAMA:

At the same debate, the Illinois senator did not try to pronounce Medvedev's name, but said the new leader "is somebody who was hand-picked by Putin."

"Putin has been very clear that he will continue to have the strongest hand in Russia in terms of running the government," he said.

REPUBLICAN SEN. JOHN MCCAIN:

The Arizona senator, long critical of Putin, had harsh words for the Russian leader on February 15.

"I think that Mr. Putin is trying to restore the old Russian empire. Obviously he is perpetuating himself in power in Russia virtually indefinitely by this setup of having basically a protege, someone who is doing his bidding as president while he serves as the prime minister," McCain said.

"We knew the puppet show was going on, we just didn't know who the puppet was."

(To read more about the U.S. political campaign, visit Reuters "Tales from the Trail: 2008" online at blogs.reuters.com/trail08/)

(Reporting by Jeff Mason and Steve Holland; Editing by Eric Beech)