Reform UK could take the government to court to prevent migrants being housed in areas where it now controls the local council. Chairman Zia Yusuf said his party will "resist" housing asylum seekers in Reform-controlled areas.
He vowed they would use "every instrument of power available", including judicial reviews, to fulfil its pledge. The Home Office is responsible for housing adult asylum seekers and while councils can object, they have little power to stop it.
Reform gained more than 600 seats and took control of 10 local authorities in Thursday's local elections.
Asked how Reform could fulfil its pledge to voters, given that contracts to house asylum seekers in hotels were drawn up between the Home Office and accommodation providers, Yusuf said the party was "realistic" about the challenge.
"The levers of power at a local level pale in comparison to the levers of power at Westminster," he told the BBC's Sunday with Laura Kuenssberg programme.
But he said "those levers of power will be pulled with all our might by Reform councillors," adding: "There are things you can do, there are judicial reviews, there are injunctions... things around planning, budget allocation."
Mr Yusuf added: "A lot of these hotels... you suddenly turn them into something else which is essentially a hostel that falls foul of any number of regulations - that's what our teams of lawyers are exploring at the moment."
Asked if Reform UK's policy was to house migrants in tents, as the party's newly elected Greater Lincolnshire mayor Dame Andrea Jenkyns suggested, Yusuf said: "That's what France does."
He added: "We will be publishing a plan to deport everybody who is currently in this country illegally in our first term of government.
"We will publish that plan in the coming weeks and you'll see the full detail."
Reform UK’s newly elected Greater Lincolnshire mayor Dame Andrea Jenkyns has said it should be “tents not rent” for asylum seekers who come to the UK.
She was asked about her previous comments that asylum seekers should not be put up in hotels and that tents are “good enough for France”.
Put to her that the French public dislike seeing people living in tents, Dame Andrea told LBC: “My whole point of making this statement is that we are soft-touch Britain and, you know, we’re acting like bees to honey by putting people in hotels.”
She added: “This is taxpayers’ money and and it should actually be tents, not rent.”