Senate Minority Whip Dick Durbin of Illinois said that he hopes the pope's message may help make climate change a less divisive and partisan issue, adding that "if he inspires us to consider policy, that will be a very successful effort."
Given the early reviews, even the pope won't be able to slice through the partisanship on climate change.
The leaked draft of the encyclical firmly states that climate change is caused by greenhouse-gas emissions linked to human activities. The vast majority of scientists agree with that claim, but Republican skeptics on Capitol Hill say that the science is far from settled.
Rep. Steve King of Iowa, a practicing Catholic, said he wasn't sure this is an area in which the church should be engaged.
"When you talk about unpredictable science, I have to ask where's the nexus between that and the theology of the Vatican?" King said. "I've studied the science "¦ and I doubt the pope is going to embrace my position. But this is science, not theology."
"I don't agree with the pope," said Sen. James Inhofe of Oklahoma, chairman of the Senate Environment and Public Works Committee and one of Congress' most outspoken climate skeptics. "I'm not a Catholic, but I've got a lot of friends who are, who are wondering: Why all of a sudden is he involved in this? I don't have the answer for that.
"I can't crawl in his mind. He has the right to say anything he wants, but that doesn't change the lack of science," Inhofe added.
The pope has made clear that he hopes his encyclical will pave the way for a strong climate deal later this year when diplomats descend on Paris for United Nations talks.
Sen. Roger Wicker of Mississippi, another climate skeptic, is wary of any kind of international climate deal on par with the Kyoto Protocol, a global treaty that committed industrialized nations to fighting global warming by reining in greenhouse-gas emissions but did not require developing nations such as China to do the same.
"I don't know what the encyclical is going to say, but basically if it advocates a Kyoto-type approach to climate change, I think a lot of needy humans are going to be put out of work," said Wicker. "It concerns me when someone who has a lot of credibility and goodwill takes a position that I think may end up harming people."
By contrast, Democratic Rep. Raul Grijalva, the ranking member on the House Natural Resources Committee, said the document should have a global reach, especially by focusing on the impact on developing countries. With Francis' focus on the poor, Grijalva said the document could lead to meaningful impacts for communities devastated by climate change.
"We're talking about a worldwide reaction to his speech, not just in the United States," Grijalva said. "In the Third World and developing countries, that's where the destruction is occurring. By being an encyclical, it becomes part of the agenda for the pope and the Catholic Church."