With 82 percent of the caucus counted on the Democratic side, CNN projected Clinton, the New York senator, the winner with 51 percent to 45 percent for Sen. Barack Obama of Illinois and 4 percent for former North Carolina Sen. John Edwards. Rep. Dennis Kucinich of Ohio failed to register even 1 percent.
With 38 percent of GOP caucuses counted, CNN gave the nod to Romney, a former Massachusetts governor, who had 53 percent to 13 percent for Sen. John McCain of Arizona, 13 percent for Rep. Ron Paul of Texas, 8 percent for former Arkansas Gov. Mike Huckabee, 7 percent for former Sen. Fred Thompson of Tennessee and 4 percent for former New York Mayor Rudy Giuliani.
It is Romney's second straight win, following his victory in the Michigan primary Tuesday.
On the Democratic side, political observers said the caucuses were a test of Clinton's and Obama's strategies for winning over Hispanics. The two rivals bombarded Nevada voters with Spanish-language ads, each claiming to be more committed to the concerns of Hispanics, The Washington Post reported Saturday.
The Nevada caucuses are seen as a preview of the battle looming Feb. 5, in which Hispanic voters could figure prominently in the California, New York and New Jersey primaries, the Post said.