U.S. scientists have expressed resentment over President Barak Obama’s administration’s plan to slash funding for planetary science at NASA by 20 percent and eliminate a major partnership with Europe on a Mars exploration program, according to the Washington Post Thursday.

The White House proposed a budget cut of $1.5 billion this year and $1.2 billion in 2013 with further declines continuing through 2017. If the proposal gets approved by Congress, NASA will withdraw from the Mars expedition project with the European Space Agency (ESA).

According to a deal NASA and ESA signed in 2009, NASA would contribute $1.4 billion and ESA would supply $1.2 billion to the project which aims to send an orbiter to Mars in 2016 followed by a pair of rovers in 2018. However, if the budget reduction gets confirmed, NASA/ESA Mars collaboration will disappear.

“In response to the federal government’s decision to reduce spending on the project, NASA is reassessing the current Mars exploration initiatives,” said spokesman David Weaver in an interview with the Washington Post.

Whether the proposal will be approved by Congress or not is unknown, but there is rising opposition from U.S. scientists. “The direct result of the budget reduction will only break with ESA. This would be a scientific tragedy and a national shock,” Scott Hubbard, director of NASA’s first Mars program, said.

"To me, it's totally irrational and unjustified," said Edward Weiler, who until September was NASA's associate administrator for science. "We are the only country on this planet that has the demonstrated ability to land on another planet, namely Mars. It is a national prestige issue."