WASHINTON (CNN) -- Former New York City Mayor Rudy Giuliani has opened up a double-digit lead over Arizona Sen. John McCain in the race for the GOP presidential nomination, a new CNN/Opinion Research Corporation poll out Monday indicates.

Thirty-four percent of registered Republicans support Giuliani, while 18 percent support McCain, the poll finds. Former House Speaker Newt Gingrich of Georgia and former Massachusetts Gov. Mitt Romney are each tied at nine percent in the poll.

In a similar CNN/Opinion Research Corporation poll conducted at the end of January, McCain trailed Giuliani by only six percentage points, registering 26 percent to Giuliani's 34 percent.

Nebraska Sen. Chuck Hagel, who announced earlier Monday he would decide whether to wage a presidential bid "later this year,' registered at two percent.

Texas Republican Rep. Ron Paul, who formally announced his White House bid on C-SPAN Monday, also registers at two percent in the poll.

The poll, conducted on March 9-11, surveyed 401 registered Republicans or Independents who lean Republican, and carries a margin of error of plus or minus five percentage points.

Full results:

Giuliani      34%
McCain        18%
Gingrich       9%
Romney         9%
Pataki         3%
Gilmore        2%
Brownback      2%
Hagel          2%
Paul           2%
Huckabee       1%
Tancredo       1%
Thompson       1%
Hunter         *    

ASTERISK MEANS LESS THAN ONE HALF OF ONE PERCENT