Hillary Clinton got some extra superdelegates Wednesday.

(CNN) — Tennessee Rep. John Tanner announced Wednesday he is backing Hillary Clinton's White House bid.

Tanner, a Democrat representing Tennessee's 8th District, is one of the more than 700 party superdelegates who will ultimately decide which candidate wins the Democratic presidential nomination.

"In my opinion, the best person to lead this critical effort is Hillary Clinton," Tanner said in a statement released by the Clinton campaign. "Hillary is a smart, pragmatic leader who understands the grave situation our country faces, with a $9 trillion debt, much of which is borrowed from foreign countries. Now, more than ever, our nation needs a leader like Sen. Clinton who can work with others to return to fiscal sanity."

Clinton won the state of Tennessee with 54 percent of the vote on February 5.

WASHINGTON (CNN) — As Sens. Hillary Clinton and Barack Obama crisscross the country accumulating both votes and delegates, the two Democratic presidential hopefuls are discovering that the actual number of delegates needed to win the nomination, the so-called "magic number," is a constantly moving target.

What does it take to win? As of today, 4,047 delegates will vote for the nominee, according to the Democratic National Committee. That means that a candidate needs 2,024 delegate votes to win. These numbers do not include Florida and Michigan, which will be adjusted if the states hold races in compliance with DNC rules.

The new totals are the result in small changes in party membership in several states, including the home states of both candidates. The newest Illinois superdelegate, Rep. Bill Foster, pledged his support to Obama, who helped him win the seat of former House Speaker Denny Hastert.

Clinton lost a superdelegate vote in New York with the resignation of Eliot Spitzer as governor, since Gov. David Paterson is a DNC member at-large who already had a vote. Paterson previously pledged his support for the New York senator.

Other changes include the addition of newly elected Indiana Rep. Andre Carson, grandson of the late Rep. Julia Carson. He remains uncommitted. John Melcher of Montana will represent National Democratic Seniors Coordinating Council, adding one more superdelegate vote for the Big Sky State. Former DNC chairman and Clinton supporter Ken Curtis lost his vote because he moved to Florida.

CNN also updated its Iowa delegate estimate based on results from county conventions held Saturday. Obama gained seven additional delegates for a revised total of 23, while Clinton lost one delegate, dropping her Iowa delegate total to 14, according to CNN estimates. Former Senator John Edwards held on to eight delegates, down from the 14 delegates CNN originally had estimated he won at the precinct caucuses on January 3.

CNN currently estimates Obama with 1,618 votes (1,411 pledged, 207 Superdelegates) and Clinton with 1,479 (1,242 pledged, 237 Superdelegates).

Click here for a breakdown of delegates by state.