The House Appropriations Committee has proposed scrapping the James Webb Space Telescope, the successor to Hubble and the flagship project of US astronomy.
The proposal comes as part of a draft budget which sees NASA's budget for next year slashed by $1.6 billion to $16.8 billion. It could be confirmed as early as today.
"Given this time of fiscal crisis, it is also important that Congress make tough decisions to cut programs where necessary to give priority to programs with broad national reach that have the most benefit to the American people," says House Appropriations Chairman Hal Rogers.
The infrared telescope would be 100 times more powerful than Hubble, with a 6.5 meter foldable mirror - which the team has just finished polishing.
It should be able to see right back to the Big Bang, and the formation of early planetary systems.
The telescope was originally due to launch in 2014, but costs have mounted and deadlines slipped. It's now not expected to launch until at least 2018, with many observers suggesting it could take much longer.
Late last year, an independent review panel found that the project was running at one-third over its $5 billion budget, thanks to organizational mismanagement.
The House will vote today on the draft bill, which will be considered by the full House Appropriations Committee next week. Even if it passes, though, it will need to be harmonized with the as yet unreleased Senate Bill.