(Bloomberg) -- Prime Minister Boris Johnson abandoned a controversial plan to build a tunnel or bridge between Scotland and Northern Ireland, saying it is now last on his list of ambitions for U.K. infrastructure projects. 

The proposed link, dubbed the “world’s most stupid tunnel” by the prime minister’s former chief adviser Dominic Cummings, has long divided opinion over its feasibility and a reported price tag of at least 15 billion pounds ($21 billion). The Financial Times reported this month the idea was vetoed as part of a Treasury crackdown on public spending in the wake of the pandemic. 

“What I would say perhaps about the tunnel/bridge is perhaps -- although it remains an ambition -- it’s not the most immediate,” Johnson told reporters during his trip to New York on Wednesday.

Though the idea has been shut down at a relatively early stage, it’s still a potential setback for a prime minister known for his love of infrastructure projects. Johnson presented the idea as a way to strengthen Northern Ireland’s links to mainland Britain after Brexit, and to bolster the unionist cause in Scotland amid an ongoing push there for independence.

Johnson appeared more optimistic that the second part of a high-speed rail project, known as HS2, would go ahead in full.

U.K. Business Condemns Talk of Scaling Back High-Speed Rail Plan

Work on the first section of the new line between London and Birmingham is already underway, and will later extend north to Manchester. But officials have failed to put to rest speculation that the eastern part of the Y-shaped HS2 layout, from Birmingham to Leeds via cities in England’s East Midlands, may be delayed or canceled due to the cost.

“You’ll have to wait until the spending review and the integrated rail plan which is also coming out,” Johnson said. “But it will be wonderful for all parts of the North, the North East, North West, Leeds, Nottingham, Derby, everywhere, Newcastle, Liverpool, Manchester, we have wonderful plans.”

Britain’s biggest business lobby has called for the government to commit in full to HS2, even as the estimated cost rises above 100 billion pounds. Proponents of the 225-mile-per-hour line say it is critical to boosting links between London and northern England, which includes parliamentary seats that switched to Johnson’s ruling Conservatives in the last general election.

Critics say the money would be better spent on upgrading existing lines and on other infrastructure.

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