The Conservative Party presents no shortage of weaknesses and Jeremy Corbyn targeted most of them at today's PMQs. Though some commentators advised the Labour leader to challenge Theresa May over Brexit (after the Prime Minister refused to say whether she would vote Leave in a second EU referendum), Corbyn wisely led on Universal Credit.

The troubled welfare system is a subject of increasing anxiety among Conservatives (12 Tory MPs have called for the roll-out to be paused) and, unlike Brexit, does not divide the opposition. Universal Credit, Corbyn warned, was increasing "debt, poverty and homelessness". "Does the PM accept it would be irresponsible to press on regardless?" he asked.

When May responded by defending the system in theory, rather than practice, Corbyn retorted: "I wonder which planet the Prime Minister is on?" The Citizens Advice Bureau, he noted, had described Universal Credit as a "disaster waiting to happen". John Major had denounced it as "operationally messy, socially unfair and unforgiving". May replied that half of claimants were now receiving advance payments (rather than waiting six weeks) but conceded, with English understatement, that "there have been some issues to address in the rolling out of this particular benefit". Not least, as Corbyn noted, the 55p-a-minute helpline (which he called for May to scrap).

In a familiar sign of weakness, the Prime Minister was happier attacking the last Labour government's record than defending her own. "The welfare bill went up by 60 per cent in real terms, which cost every household an extra £3,000 a year," she declared. But Corbyn, who is sometimes accused of avoiding any praise of the last Labour government, recalled that it "lifted a million children out of poverty".

For his last question, Corbyn broadened his focus, tearing into the Tories with the relish of 1990s-era Blair. "Everywhere you look it's a government in chaos," he declared, citing Brexit, Bombardier and the social care crisis. "This government is more interested in fighting among themselves than solving these problems," he concluded. "Isn't it the case that if the Prime Minister can't lead, she should leave?" May delivered a fierce response, taking in Labour anti-Semitism and John McDonnell's preparations for a "run on the pound", but she could not disguise the sense of decay around her government.

As confirmation of Corbyn's good instincts, Conservative rebel Heidi Allen immediately followed him and urged May to abolish the six week Universal Credit waiting period. If the Prime Minister fails to soon choose between leading and leaving, her MPs may yet answer the question for her.