The party's continued prominence has brought what prominence always brings: scrutiny, says BBC political editor Chris Mason.
Some MPs have pressed for the government to introduce a cap on UK-based donors.
The PM said his government would be "grounded in fiscal responsibility" as he faced Kemi Badenoch at Prime Minister's Questions for the first time.
The Reform UK leader said a "whole ecosystem" didn't want "new kids on the block succeeding".
The Reform leader has been dogged by questions over his finances after receiving a £5 million sum from Christopher Harborne.
Burnham's exchanges with Kemi Badenoch slipped into familiar territory of trading barbs, writes Alex Forsyth.
Huge AI spending plans and the ongoing war in Iran are driving up borrowing costs around the world.
Curiously, the questions at lunchtime may well feel like a minor extension of what he faced on Tuesday, the BBC's political editor writes.
Higher borrowing costs have piled fresh pressure on Andy Burnham ahead of his first Budget.
Tory leader Kemi Badenoch said Burnham was offering "more government control, more taxes and more politicians", as he addressed MPs for the first time as PM.
The prime minister's first appearance in Parliament comes more than six weeks after he entered No 10.
The move will trigger a by-election to replace the former prime minister in his London constituency.
Kemi Badenoch is expected to carry out a wider reshuffle of her front bench team following high-profile departures.
A survey by the party suggested almost half of teachers reported considering quitting the classroom in the next five years.
Andy Burnham tells BBC Breakfast anyone convicted of manslaughter will be excluded from the early release scheme in the Sentencing Act.
The prime minister says he will keep hundreds more criminals behind bars but doing so requires complex changes.
The imminent return of Parliament will put the new prime minister under real scrutiny, with MPs finally getting a chance to grill him.
Millions across England and Wales received a wildfire alert on their phones earlier this month, but it partly backfired.
Burnham has called for all views to be respected as MPs vote in two weeks on legalising assisted dying in England and Wales.
The draft bill would be introduced into Parliament if the Scottish government secured the necessary powers from the UK government.