President Obama is urging Americans to make climate change a political litmus test, asking them to declare they won't vote for any politicians who don't protect future generations from environmental devastation.

Obama says Americans are already paying the price for climate change, including in lost lives and hundreds of billions of dollars. He says America will be judged as a people and a nation by how it responds.

"If you agree with me, I'll need you to act," Obama says, appealing to Americans to spread the word to their family, friends and classmates. "Remind everyone who represents you, at every level of government, that there is no contradiction between a sound environment and a strong economy -- and that sheltering future generations against the ravages of climate change is a prerequisite for your vote."

Obama's remarks in his weekly radio and Internet address, released Saturday but recorded at the White House prior to the start of Obama's weeklong trip to Africa, marks the start of a new phase for Obama's efforts on climate change: convincing the public to sell it for him.

Obama last week unveiled a national plan to combat climate change and prepare for its effects, bypassing Congress after years of frustrated efforts to get lawmakers to pass legislation to deal with the issue. At the core of Obama's plan are new controls on new and existing power plants that emit carbon dioxide -- heat-trapping gases blamed for global warming. The program also will boost renewable energy production on federal lands, increase efficiency standards and prepare communities to deal with higher temperatures.

None of the measures in Obama's plan require Congress to act -- a consideration that liberates the president but also poses risks if it's perceived as executive overreach. Republicans and some Democrats have already denounced the plan as a job-killing "war on coal," and opponents could try to hinder Obama's plan or hinder it through legal action if Americans don't seem to be on board.

"The question is not whether we need to act. The question is whether we will have the courage to act before it's too late," Obama says, adding that a sound environment and a strong economy aren't mutually exclusive.

In the Republican address, Sen. Pat Roberts of Kansas says there are troubling, unanswered questions about the implementation of Obama's health care law.

"We must put an end to the fear and uncertainty," Roberts says. "Those `bumps' and `glitches' the president talks about? It's a train wreck, folks, and we have to get America out of the way."