The Conservatives say they will not support a bid for more Welsh powers on housing unless two clauses are removed.
It comes as a call was made for cross party unity to tackle homelessness by Secretary of State Peter Hain.
Mr Hain is urging all parties to back a bid from Wales for more housing powers before the dissolution of parliament.
But the Conservatives object to clauses to suspend the right to buy and one which could allow Gypsy sites to be built contrary to local decisions.