By Dan Gilgoff, CNN.com Religion Editor

(CNN) - Texas Gov. Rick Perry, who recently attracted national attention for publicly mixing Christianity and politics, is putting some of his money where his mouth is - but not, critics say, very much.

According to an analysis of his tax returns by the San Antonio Express-News, the Republican Perry has given half a percent of the $2.68 million he earned as governor to churches and religious organizations.

Here's the Express-News:

By comparison, Americans averaged gifts of nearly 1.2 percent of their income to churches and religious groups from 2004 to 2008, according to Empty Tomb Inc., an Illinois-based research firm specializing in U.S. church-giving trends.

In 2007 — a year in which Perry reported an income of more than $1 million — he gave $90 to his church, according to the Perry family's tax return. Twice since becoming governor, in 2000 and 2009, he reported no contributions to churches or religious organizations.

Speculation about whether Perry, the longest-serving governor in Texas history, will join the Republican presidential field is intensifying, as more and more Republicans encourage him to enter the fray.

Earlier this month, Perry made national headlines by partnering with a conservative Christian group to host a forthcoming prayer event at Houston's Reliant Stadium.

"America is in crisis, " the governor says on a website promoting the event. "We have been besieged by financial debt, terrorism, and a multitude of natural disasters."

The Express-News quotes critics of Perry who say his modest giving despite his outspoken Christian faith makes him a hypocrite. The paper also suggests the revelations about his charitable donations may cause him political problems among his Christian supporters:

His track record could be a problem said Michael Lindsay, incoming president of Gordon College and author of “Faith in the Halls of Power,” about the growth of evangelical politics. “He's going to have a hard time with this,” Lindsay said. “While that may be acceptable for someone who does not aspire to leadership, evangelicals get very concerned when their leaders don't walk the talk.”

What do you think? Will Perry's modest giving be an issue for his Christian supporters, especially if he runs for president? Should it be an issue?