(CNN) – It was meant to be a prebuttal to Vice President Joe Biden's Thursday campaign stop in New Hampshire, but former Granite State governor John Sununu, a Mitt Romney supporter, used the opportunity to slam the president for his record in donating to charity.
"One would hope that they would at least demonstrate some real concern for the needy," Sununu said of Biden and President Barack Obama on the call, which was scheduled ahead of Biden's Thursday stop in Exeter.
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Much of Biden's address is built around the Buffett Rule, which would institute a 30% tax rate on Americans making more than $1 million per year.
Sununu said the measure echoed false in light of what he said were paltry charitable donations from Obama and Biden.
"In their private lives it would be nice to see some contributions to charity that are significant out of President Obama and Joe Biden," Sununu said. "I think it's an interesting contrast to make with the presidential candidate Republicans now have put together a nomination for, is Mitt Romney, who gave almost 15% of his income last year to charity."
An examination of the two candidates' tax returns shows comparable records of charitable donations.
Obama gave $245,075, or 14.2% of his $1.7 million in income to charity in 2010, the only year tax returns are available for all three candidates. Romney donated almost $3 million, or 13.8% of his income.
In addition to his 2010 return, Romney has released an estimate for 2011.
The deep-pocketed former Bain executive gave $2.98 million in 2010, and $4.02 million the following year. That works out to 16.4% of his $42.6 million in aggregate income over the two-year period. Romney's charitable donations include large portions given to the Church of Jesus Christ of Latter-Day Saints, of which he is a member.
Biden and his wife, Dr. Jill Biden, earned far less than Obama and Romney in 2010, and donated a much lower percentage of their income to charity. The couple reported an adjusted gross income of $379,178 in 2010, and donated 1.4% of that to charity.
CNNMoney's Charles Riley contributed to this report.