Migrants wanting to become Australians have been given an assurance that their applications will be processed under the current rules.

Immigration Minister Peter Dutton confirmed to ABC News this evening that applications received after April 20 would be processed under existing laws following the rejection of amendments by the Senate.

The decision is a significant backdown from the Federal Government, following its announcement in April of planned changes that would have made it harder to become an Australian.

The proposal would have required applicants to live in Australia for four years on permanent residency visas and demonstrate "competence" in English.

Mr Dutton had sought to apply the changes to all people who applied from April 20, but he could not secure support from the Senate.

A last-minute proposal by Mr Dutton this afternoon, hours before a parliamentary deadline to keep his bill alive, was rejected by the Senate crossbench.

These amendments to the initial bill reduced the English competency required by applicants from "competent" to "modest" and changed the start date to July next year.

NXT senator Stirling Griff rejected Mr Dutton's 11th-hour attempt at compromise, and had called on the Government to start processing new citizenship applications.

"The Government did not need legislation to impose the freeze on citizenship applications and it most certainly does not need legislation to lift it," he said earlier.

"This is all self-imposed; the Government can lift the freeze any time it wants to and process those applications that are currently in limbo."

The Federal Government wanted applications received since April 20 to be processed under the proposed laws, but the reforms stalled following a Senate committee report that was critical of the proposal.