WASHINGTON -- The race for the 2008 Republican presidential nomination has become wide open, a new Wall Street Journal/NBC News poll shows. But the value of winning it has fallen sharply.

The survey shows that without formally entering the race, former Tennessee Sen. Fred Thompson has risen to second place in the Republican field. Former New York City Mayor Rudy Giuliani continues to leak support, but leads the pack with 29% to Mr. Thompson's 20%, while former Massachusetts Gov. Mitt Romney has pulled even with Sen. John McCain...