Tax credit cuts will cause unacceptable "suffering" for poorer families, Ruth Davidson has warned.
The Scottish Conservative leader is the latest Tory to voice concern over the policy.
Ms Davidson said the cuts were necessary but needed to be introduced more carefully.
"It's not acceptable. The aim is sound, but we can't have people suffering on the way," she told the Mail on Sunday.
"The idea that there's a cliff edge in April before the uptake in wages comes in is a real practical human problem and the Government needs to look again at it."
They are not there to interfere with the settled will of the House of Commons, warned Boris Johnson.
A working mum who would be hit by Tax Credit cuts spoke to ITV News ahead of the House of Lords vote on the changes.
Peers will have to decide whether to delay changes to the tax credits bill, review them or scrap it altogether.