Dutton stands by subs call amid criticism

Heavy criticism from senior US senators hasn't dissuaded Peter Dutton's belief America should sell Australia Virginia-class submarines to avoid a looming capability gap.

The opposition leader maintains that the option remains on the table, despite suggestions the AUKUS pact was pushing the US submarine-building industry to "breaking point".

Two members of the US armed services committee - Democratic Senator Jack Reed and Republican Senator James Inhofe - wrote to President Joe Biden late last year.

They implored him to not let the security pact between the two nations and the United Kingdom to come at a cost to their own capability.

Australia continues to shape an "optimal pathway" to make sure there's no capability gap between the retirement of current submarines and the nuclear-powered vessels, not scheduled for completion until 2040.

Asked on Sunday if he stood by his claim Australia can fill the gap by buying two Virginia-class boats by 2030, Mr Dutton said Prime Minister Anthony Albanese must continue pushing that case with America.

"There's no question in my mind, that option is still on the table, the ability to make sure we can keep our reach in sight is really dependent on the acquisition of those assets," he told reporters.

"We should continue to work very closely to achieve an outcome and acknowledge the US and other partners have their own obligations and their own needs but we are a trusted, reliable partner and that's why the AUKUS deal was struck in the first place."

Defence Minister Richard Marles said on Saturday both the US and the UK were committed to making sure Australia didn't have a capability gap.

"There are lots of challenges and there's no doubt the pressure this places on the industrial base of the United States, also the United Kingdom, is really significant," he told reporters.

"Last year, I met with Senators Reed and Inhofe, they are both very strong supporters of Australia and really I have no doubt, at the end of the day, we will be able to deliver this."