Suella Braverman pledged to cut migration by tens of thousands, despite the failure of successive governments to hit the same target.
The Home Secretary said she would aspire to reduce net migration from the current level of 239,000 amid a growing clamour from Tory activists for the party to take control.
She was also forced to admit that the Conservative plan to send people seeking asylum to Rwanda will not happen “for a long time”.
In an appearance at a conference fringe meeting, The Guardian reported Braverman saying: “In the 90s it was in the tens of thousands under Mrs Thatcher – net migration – and David Cameron famously said tens of thousands, no ifs no buts.
“So that would be my ultimate aspiration but we’ve got to take it slowly and we’ve got to go incrementally.
“I think we have got to definitely substantially reduce the number of students, the number of work visas and in particular the number of dependants on those sorts of visas.”
At the conference, Braverman used her first major speech to say migrants crossing the Channel will face a ban from claiming asylum in Britain.
The new laws – which go further than the Nationality and Borders Act which came into force in June – will impose a blanket ban on anyone deemed entering the UK illegally from seeking refuge.
The announcement marks the latest attempt by ministers to curb the growing numbers of crossings after its flagship policy to send migrants on a one-way trip to Rwanda stalled amid legal challenges.
So far this year more than 33,500 people have arrived in the UK after making the journey from France.
Braverman told the conference in Birmingham: “We have got to stop the boats crossing the Channel. This has gone on far too long.
“But I have to be straight with you: there are no quick fixes and the problem is chronic.”
She said the law “simply isn’t working” and legislation was being “abused” by people smugglers, people making “multiple, meritless and last-minute claims” and – taking aim at lawyers – by “specialist small boat-chasing law firms”, adding: “This cannot continue.”