John McCain continues to hold a 15-point advantage over Mitt Romney on the Republican side. Jan. 29-31 Gallup Poll Daily tracking data show 39% of GOP voters nationwide favoring McCain for the nomination, while 24% support Romney and 17% Mike Huckabee. It appears McCain is the primary beneficiary of Rudy Giuliani’s campaign exit, not surprising since Giuliani endorsed McCain. McCain’s support has increased by seven points compared with the Jan. 27-29 data (the last in which Giuliani was included in all three nights of interviewing). Romney’s support has increased three points since then, and Huckabee’s has gone down one point. It is difficult to assess the precise impact of Giuliani’s departure since it essentially occurred simultaneously with McCain’s win in the crucial Florida primary held Tuesday. — Jeff Jones