The House of Representatives has passed a proposal that will stop the NSA from appropriating funds to conduct backdoor communications searches on Americans without a warrant. An amendment to the 2015 Defense appropriations bill, the proposal will basically stop the Agency from using its allocated budget in two key ways. The first of which is conducting warrantless searches of this nature and secondly, to prevent the NSA from forcing hardware/software companies to give it access via built-in security loopholes.
Reports suggest the proposal doesn't actually prevent the NSA from conducting back door searches, instead it just cuts the funding to both activities. However, if it makes it through the Senate and President Obama to become law, it will technically shut down both operations.
The surprise bi-partisan vote, which came in at 293 in favor and 123 against, has been labelled by some as a sign of how discontent Congress is with the backdoor tracking of US communications by the NSA. Similar amendments didn't fair so well with Congress in the past, but now after a year or so of reports from leaked Snowden documents, sentiment in the House is beginning to sway. It is also likely in response to the USA Freedom Act, which many considered a watered down approach to reining in NSA surveillance activity in the US.