Barack ObamaBarack Hussein ObamaObama warns of a 'decade of unfair, partisan gerrymandering' in call to look at down-ballot races Quinnipiac polls show Trump leading Biden in Texas, deadlocked race in Ohio Poll: Trump opens up 6-point lead over Biden in Iowa MORE is getting more visitors to his website and more mentions on blogs than John McCainJohn Sidney McCainAnalysis: Biden victory, Democratic sweep would bring biggest boost to economy The Memo: Trump's strengths complicate election picture Mark Kelly: Arizona Senate race winner should be sworn in 'promptly' MORE, according to Nielsen's Internet ratings.

Obama's site received 2.3 million unique visitors while McCain's got 563,000 during May, according to Nielsen. Obama also received about double the amount of mentions on blogs and discussion boards than McCain.

"Barack Obama got a head start during primary season in using the Web effectively to garner support, both in terms of votes and donations,