Kemi Badenoch was accused of asking "fantasy questions" as she made a bizarre bid to blame Labour for Tory council tax rises.
The Tory leader accused Keir Starmer of secretly planning to increase the cap on council tax rises - which was set at 5% by the Tories. Number 10 says they have no plans to increase the cap.
And Ms Badenoch's team admits they have no idea how they would fill the funding gap she claims exists in local goverment budgets.
The Tories set the current cap on council tax increases at 5% at Jeremy Hunt's last budget - setting it at the same level it has been at for several years.
Ms Badenoch's argument is based on a answers to parliamentary questions, in which ministers said local government's estimated "core spending power" would go up from £64.7 billion to £68.4 billion over the next year.
But ministers explained this figure was subject to change and the final figure wouldn't be published until next year.
Speaking at PMQs, Mrs Badenoch asked: "Will the Prime Minister confirm that he will keep the cap on council tax?"
Sir Keir, in his reply, said: "On the question of councils, she knows what the arrangements are."
Asked whether there were any plans to change the cap in a briefing after PMQs, Number 10 said: "No change."
Ms Badenoch also noted the Labour group on the Local Government Association had called for the cap to be increased, because in their view the current level would leave a shortfall in cash available to spend on social care.
But she didn't mention that the Conservative Group on the Local Government Association also called for the cap to be lifted.
In fact, their 2025 plan calls for the cap to be removed entirely - allowing councils to increase council tax by as much as they like. The document says this would "allow councillors to be held accountable for their decisions on taxation at the ballot box".
Asked what Ms Badenoch's plan to fill the "£2.4 billion hole" she claims exists in local council budgets, her spokesman said: "It's not for us to. We are in opposition. It is for the government."
Be the first with news from Mirror Politics
US ELECTION WHATSAPP: Join our US Election WhatsApp group here to be first to get all the biggest news and results as America heads to the polls. We also treat our community members to special offers, promotions, and adverts from us and our partners. If you don’t like our community, you can check out any time you like. If you’re curious, you can read our Privacy Notice.
POLITICS WHATSAPP: Be first to get the biggest bombshells and breaking news by joining our Politics WhatsApp group here. We also treat our community members to special offers, promotions, and adverts from us and our partners. If you don’t like our community, you can check out any time you like. If you’re curious, you can read our Privacy Notice.
NEWSLETTER: Or sign up here to the Mirror's Politics newsletter for all the best exclusives and opinions straight to your inbox.
PODCAST: And listen to our exciting new political podcast The Division Bell, hosted by Mirror interim political editor Lizzy Buchan and Express political editor Sam Lister, every Thursday.