Labour is starting to turn against the more draconian elements of the immigration bill following the shock resignation of Mark Harper.
The immigration minister returned to the backbenches yesterday after he discovered his cleaner was an undocumented immigrant.
The development was particularly embarrassing given the immigration bill forces landlords, driving licence authorities and GPs to verify people's immigration status.
"I understand and respect the decision Mark Harper has taken today," shadow immigration minister David Hanson said.
"As immigration minister he has argued in parliament for landlords to be required to carry out checks on every tenant.
"So this information about Mark Harper's employee does put him in a difficult position."
Labour is calling for the landlord scheme to be piloted before implementation and extra funding for an immigration status helpline but Hanson's statement suggested the party might be prepared to adopt a stronger opposition to the move.
"[Harper] has shown himself to be a decent man in his resignation and I wish him well for the future but perhaps once again the government need to think very carefully about how they approach this issue as it is clear there are limits to the effectiveness of relying on employer and landlord checks to address illegal immigration," Hanson said.
Labour will be wary of voting against the measures in the bill, which would allow the Conservatives to portray the party as 'soft' on immigration ahead of the general election.
But the slight shift in Labour rhetoric on the proposal for landlord checks suggests the Harper resignation may have triggered a change of heart in Labour HQ.
Labour sources said they had already put down a series of amendments concerning the landlord checks, which would soon be debated in the Lords.
Harper said he checked the immigration status of his cleaner before she started working for him in 2007, including taking a copy of her passport and a Home Office letter. He said he did so again in 2012 when he became immigration minister.
"In the week commencing January 20th 2014 I asked my cleaner for further copies of these documents which she provided on February 4th," he wrote to the prime minister.
"On February 5th, I asked my private office to check the details with immigration officials to confirm that all was in order.
"I was informed on the morning of February 6th that my cleaner did not in fact have indefinite leave to remain in the United Kingdom. I immediately notified the home secretary and my permanent secretary."
He added: "Although I complied with the law at all times, I consider that as immigration minister, who is taking legislation through parliament which will toughen up our immigration laws, I should hold myself to a higher standard than expected of others.
"I have also considered the impact on my parliamentary colleagues, the government and you. I have always believed that politics is a team game, not an individual sport.
"Under the circumstances, I have therefore decided that the right course is for me to return to the backbenches. I am sorry for any embarrassment caused."
David Cameron wrote back: "I am very sorry indeed to see you leave the government, but I understand your reasons for doing so.
"In particular, I understand your view that, although you carried out checks on your cleaner, you feel that you should hold yourself to an especially high standard as immigration minister. You have taken an honourable decision."
James Brokenshire was moved to the immigration brief in a mini-reshuffle following the resignation.
The immigration bill was passed by 303 votes to 18. Among the opponents were six Labour MPs and three Liberal Democrats.
Among its other measures are plans to charge temporary residents for NHS care, cut down on appeals and move them off-shore where possible and check people's immigration status before they can open a bank account.