The boss of Crossrail 2 is hoping to get the go-ahead to push on with the £30bn project by next month.
Crossrail 2 managing director Michèle Dix said there is "very good cross-party support up and down the route", and she was hoping the government will give Crossrail 2's business case and funding plan the green light in May.
Transport for London (TfL) has submitted a business case and funding plan for the project, which Dix says will have transport benefits "from the Solent to the Wash", to the transport secretary.
Speaking at a London Chambers of Commerce and Industry (LCCI) policy meeting today, Dix said: "We want a positive decision from the government further to the strategic business case, we want to get that decision in May at the latest."
If they are given the go-ahead, the Crossrail 2 team will prepare for a hybrid bill and plan to submit that to parliament by the autumn of 2019. "It should get to second reading by the election which we think is critical, as it means you get agreement on the scheme in principle," Dix said.
The timeline would plan for Royal Assent by 2021/2022 and then start building ready to open for 2033, "just in time for HS2 Phase 2 to arrive at Euston".
"Without Crossrail 2 at Euston, quite a few of the benefits gained from travelling down from the North will be lost while you wait in a queue at Euston," Dix added.
Crossrail 2 will serve stations throughout the South East, linking south west and north east London, as well as Surrey and Hertfordshire. Proponents, including the mayor, see it as critical to the capital's future rapid growth and said it will support the regeneration and development of up to 200,000 new homes across London and the South East.
The concerns the government has over the project, however, relate to balancing the funding of other commitments and the timing of the proposed hybrid bill.
"London can raise half the money, but we'll still need the government to provide the other half, so one of the concerns will be timing for that money versus commitments to other schemes, so commitments to HS2 and also ensuring they can support schemes in the North," Dix told City A.M.
"And timing of the hybrid bill will be an issue versus other schemes. We say, well actually there's over 600 MPs, you only need about six, even though Crossrail 2 does have this regional impact, you should be able to find six to do Crossrail 2 at the same time as you're finding some to do HS2 Phase 2 B. So we believe you can run the bill in parallel with another bill."
She also commented on concerns raised over London and South east projects being pitted against those in the North for funding. "We believe it's not the case of a zero sum game," she said. "It's important to invest in London and it's equally important to invest in the North."
Crossrail 1 is due to fully open in 2019.