Four Republican senators called Wednesday for an investigation of National Science Foundation grants, saying the federal agency had ventured beyond science and into political advocacy, particularly with its support of a program to encourage TV weathercasters to report on global warming.

The four senators called for the foundation’s inspector general to investigate the $4 million program to increase climate reporting by meteorologists, saying it “is not science — it is propagandizing.”

The senators — Ted Cruz of Texas, Rand Paul of Kentucky and James Lankford and Jim Inhofe, both of Oklahoma — said the program, run by the nonprofit Climate Central, epitomizes National Science Foundation grants that stray beyond their appropriate scope of “basic research.”

The demand for an investigation came the same day that NBC News reported how Climate Central had helped educate more than 500 TV weathercasters across the country on global warming and the impacts it is having on everything from temperatures to the growth of poison ivy to the amount of pollen in the air. The organization’s six-year-old program with TV weather reporters is called “Climate Matters.”

The senators' objections were made in a letter to science foundation's inspector general, Allison Lerner. It charged that the foundation had “issued several grants which seek to influence political and social debate rather than conduct scientific research.” That may have violated not only the agency’s mission but the Hatch Act, the federal law that prohibits federal employees from taking public political positions, the senators said.

Ben Strauss, CEO of Climate Central, rejected the contention that his organization engaged in politics. The foundation grants “support informal public science education concerning well-established science,” Strauss said via email. “Climate Central is not an advocacy organization, and the scientific consensus on climate change is not a political viewpoint.” He added that it was well-known that the science foundation supports science education.

The NSF grants followed a 2010 solicitation by the agency to create a Climate Change Education Partnership "devoted to increasing the adoption of effective, high quality educational programs and resources related to the science of climate change and its impacts." The foundation asserted that it would invest $20 million total in 2010 and 2011 because the impacts of climate variability are "one of the most pressing challenges of our time."

All NSF grants pass through a review process "considered to be the 'gold standard' of scientific review," an NSF spokeswoman said via email. The reviews include evaluation by at least three independent outside experts, she said.

The agency's inspector general did not respond to a request for comment.

Climate Matters holds workshops and webinars for TV climate reporters and posts weekly updates on its website about how changes in the earth’s climate could be affecting the weather, farming, human health and other variables. This week, the program was expanded to bring global warming lessons to other journalists, including newspaper and radio reporters.

The program, based at Climate Central’s offices in Princeton, N.J., is supported by academics at George Mason University's Center for Climate Change Communication and by research from NASA and the National Oceanic and Atmospheric Administration (NOAA), two other federal agencies. The senators did not address the NASA and NOAA roles in the climate change program.

The complaint from the senators cited a six-year-old opinion column in The Washington Post, which accused Climate Central of being an “advocacy group” rather than a research and educational endeavor. Strauss countered that the column had been “soundly refuted” at the time by the climate group’s then-CEO.

The senators, from left, Cruz, Paul, Lankford and Inhofe, say the program to increase climate reporting by meteorologists is beyond the National Science Foundation's scope of "basic research." AP/Reuters/CQ Roll Call

The senators saw evidence of ill intent, though, in the fact that Climate Matters targeted a group — meteorologists — who were found in an initial opinion poll to have mixed opinions about the reality of global warming.

“Having learned that meteorologists in general remained inconclusive regarding climate change, this coalition then returned to the NSF and secured an additional $2,998,178 to expand ‘the reach’ of a political advocacy group ... ,” the senators wrote. They said the science foundation’s oversight of the program was “egregious” because the agency “saw fit to fund this project designed to ‘recruit’ experts to a position they did not come to of their own accord as meteorologists.”

The weathercasters were used “to show them how an unknowledgeable citizenry would be more easily convinced of the same belief,” the senators claimed.

The senators cited several other grants that they said also encouraged “individuals to adopt a particular politicized worldview.” One had to do with “political engagement” among engineers and another with the impacts of the media on political polarization.

They asked the inspector general to answer a series of eight questions, including whether any science foundation grants constituted “engagement in political activity,” whether violations of the Hatch Act had occurred and what would be done in the future to assure “political research” is not funded by the science agency.

Sen. Sheldon Whitehouse, D-R.I., belittled the Republicans' call for an investigation.

“Calling education on the irrefutable science of climate change ‘political’ would be laughable if it didn’t reveal such a sobering truth about Republicans in Congress," Whitehouse said in a statement. "Climate deniers still exist on Capitol Hill and the way fossil fuel money holds sway over the Republican Party permits antics like attacking this sensible grant."

Weathercasters interviewed by NBC News about the Media Matters program said they thought it was worthwhile because it presented unbiased and scientifically sound information that helped them to better inform their viewers.

“It’s just scientific fact," said Steve LaPointe, an upstate New York weathercaster who received support from Climate Matters. "And the more it gets talked about, the more it’s normalized."