Senate Republicans thumbed down a Democrat-led effort to boost research and development spending that would have maintained the US' large technology edge over its rivals, especially China.

At a Senate Appropriations Committee hearing on April 29 about U.S. R&D spending, Sen. Barbara Mikulski (D-Md.), the committee chairwoman, said that much of America's "exceptionalism" sprang from its investment in science.

"We cannot afford to let other countries out-invest or out-innovate the U.S.," she said.

The White House Office of Science and Technology Policy (OSTP), the lead witness at the hearing, said that total private and public US R&D investments stood at $429 billion in 2011. China, which spent $208 billion, came second to the US. One research group believes China will surpass the U.S. in R&D spending by 2022.

John Holdren, who heads the OSTP, said China will surpass pass the U.S. "in a matter of a few years." He said the US is in real danger of being overtaken by China in R&D spending.

However, Richard Shelby (R-Ala.), Vice-Chairman of the Senate Appropriations Committee, rejected the Democrats' appeal for more R&D support, echoing the Republican's long-standing demand for spending cuts and linking federal debt and mandatory spending to any increase science spending.

Shelby claimed that an unfortunate consequence of the government's other budget problems "is the crowding out of important parts of our budget."

He had previously stressed the importance of the committee's adherence to spending limits set in a recent budget deal. Republicans claim that mandatory spending growth is the true driver of the country's debt.