"I think this is just a terrific sign about the importance of Catholics in American public life these days," said Stephen Schenk, a professor at The Catholic University of America and a national co-chair of "Catholics for Obama."
Dolan accepted an invitation from the Democratic National Convention, which runs September 4-6, to give the final benediction in Charlotte, North Carolina, after President Barack Obama accepts his party's nomination.
The cardinal also prayed at the Republican National Convention in Tampa, Florida. on Thursday after Republican presidential candidate Mitt Romney accepted his party's nomination.
While tradition suggests a local bishop, priest or religious would represent Catholicism at each party's convention, Dolan's decision to go to Tampa and Charlotte reinforces his place as the face of Catholicism in America, said Jesuit Fr Thomas Reese, a senior fellow at the Woodstock Theological Center at Georgetown University.
"Clearly, Cardinal Dolan is seen by the bishops as the spokesman for the US bishops in this country. In a sense, he's trying to be the Catholic Billy Graham," he said.
Reese told NCR that Dolan's praying with both parties projects the same "being above partisan politics" image Graham has broadcast for decades.
Dolan's appearances at the conventions are only part of his increasing presence in the political scene. He has been outspoken against a mandate from the U.S. Department of Health and Human Services requiring employer health insurance plans to provide contraceptive coverage, going as far as suing the administration over the mandate.
But in recent weeks, he also gained national attention for inviting both the president and Romney to the annual Al Smith Dinner, a major fundraising event for Catholic Charities of New York, against objections from anti-Obama Catholics.
The cardinal has also sent letters to both candidates and their running mates, asking all to sign the "Civility in America" pledge created by Carl Anderson, head of the Knights of Columbus, and focus on the issues in their campaigns.