HS2: Senior government figures meet to consider rail link
The future of HS2 will be considered at a meeting on Thursday between the prime minister, the chancellor and the transport secretary.
However, No 10 said a final decision on the rail link would not be taken then.
The BBC's political editor says the mood music seems to be pointing towards going ahead with the project but massive anxieties remain.
At Prime Minister's Questions on Wednesday, Boris Johnson said MPs could expect a decision "very shortly".
It follows a leaked review on the project suggesting it could cost almost double the £56bn originally expected in 2015.
Phase 1 of the rail line between London and Birmingham is due to open at the end of 2026, with the second phase to Leeds and Manchester scheduled for completion by 2032-33.
- HS2: Give me the facts, says Shapps
- Will HS2 ever get built?
- HS2 rail project to be reviewed
- Rail firm Northern to be nationalised
It is designed to carry trains capable of travelling at 250mph.
The government commissioned a review into the line last August, designed, ministers said, to determine whether the project could still be deemed value for money.
Billions have already been spent on it, but Transport Secretary Grant Shapps has refused to rule out scrapping it entirely.
The transport secretary revealed last week he had asked for more data before making a "massive decision" on HS2, after a leaked government review found it could cost £106bn.
The unpublished report, which was leaked to the Financial Times, said there was "considerable risk" that estimated costs could rise by another 20% - but it did conclude that despite the ballooning bill, it should still go ahead.
The government had previously promised to make a decision on HS2 before the end of 2019.
Mr Johnson faced calls to back HS2 from Conservative MPs at PMQs.
Kevin Hollinrake, MP for Thirsk and Malton, in North Yorkshire, called on the government to increase rail capacity "in and between the North, the Midlands, the South and Scotland".
This could only be done by investing in the Midlands Engine, the Northern Powerhouse and carrying on with HS2, he told the PM.
Mr Johnson said the government was looking at investing into the North and Midlands and added that MPs can "expect an announcement very shortly" on HS2.
The PM also sought to reassure Paul Howell, freshly installed as Sedgefield's new Conservative MP, who called for a "positive" decision to improve connectivity in his region.
Keiran Mullan, Tory MP for Crewe and Nantwich, urged the PM to "get HS2 done to secure jobs across the country".
Speaking earlier on BBC Politics Live, the BBC's political editor Laura Kuenssberg said the signs were that HS2 would get the go-ahead, even though there were very powerful voices critical of it high up in government.
She said it was in part a question of credibility - it would be difficult for a government which says it is committed to greater investment in the Midlands and North to cancel the biggest project on its books designed to do that.