WASHINGTON (CNN) -- Sen. Hillary Rodham Clinton would wage a tough battle against Sen. John McCain if the 2008 presidential election were held tomorrow, according to results of a CNN poll released Tuesday.

Clinton would also face stiff competition from former New York Mayor Rudolph Giuliani, but apparently would win an easy victory over Massachusetts Gov. Mitt Romney, according to results of the Opinion Research Corporation poll.

For instance, 47 percent of the 1,019 people surveyed said they would vote for Clinton, D-New York, -- and also for McCain, R-Arizona. Forty-eight percent said they would choose Clinton over Giuliani's 46 percent. But matched up against Romney, 57 percent of survey respondents said they would choose Clinton, compared to 34 percent for Romney.

The telephone poll was conducted Dec. 15-17. The sampling error is plus or minus three percentage points.

Forty-seven percent of poll respondents said they would choose McCain over Illinois Sen. Barack Obama -- compared to 43 percent for Obama -- and 49 percent said they would choose Giuliani over Obama's 42 percent. But 51 percent said they would vote for Obama over Romney, who had 35 percent.

Former presidential candidate Al Gore was locked in a virtual tie with McCain, 47 percent to 46 percent. Gore and Giuliani, meanwhile, each received 46 percent. But 53 percent said they would choose Gore over Romney, with Romney receiving support of 37 percent of poll respondents.

Democrats appear to hold an advantage at this point for 2008, with 52 percent of poll respondents saying they would either definitely vote for a Democrat or are leaning in that direction. Thirty-two percent said they were leaning toward the GOP or would definitely cast their ballots for a Republican candidate. Thirteen percent said they were not leaning toward either party.

Full poll results