The transport secretary has confirmed the government will pass the Mersey Gateway project if Labour remains in power after the general election.
Lord Adonis detailed his approval in a letter to Labour candidate Derek Twigg.
The planned six-lane toll bridge between Runcorn and Widnes is also supported by Halton Conservative candidate, Ben Jones.
Warrington South's Liberal Democrat candidate Jo Crotty said the bridge should be free for all motorists.
If it is passed, a toll would be introduced on the existing Silver Jubilee Bridge to help pay for the additional £431m crossing.
Ms Crotty said: "I fully support the bridge project - as it completes the network of motorways and should hopefully reduce some of the congestion in Warrington and over the Silver Jubilee Bridge.
"However, I do not agree with the way Labour has decided to fund it - by use of a private finance initiative.
"If the government just funded it from taxpayers' money - like they have done for a bridge in Scotland - there would be no interest to pay back so the toll would not be necessary."
Ben Jones said without the tolls there would be no bridge.
"Since becoming the area's candidate in November 2008, I have strongly supported the idea of a new bridge that will bring thousands of new jobs and really boost our local economy.
"We need to charge some kind of toll otherwise the bridge will not be built. But I can say if the Tories get into power I will be campaigning for the best possible deal for local people."
Derek Twigg said: "We need to charge some kind of fee to ensure we can pay for the bridge.
"Once the plans have been passed the toll amount can be assessed and obviously we will be looking into ensuring discounts for local people and keep the price down."
The Mersey Gateway proposals are currently with the government for final approval.
The bridge will be 1km (0.6 miles) long, crossing the River Mersey and nearby the canals.
Construction could start by 2011.
Parliamentary candidates announced so far:
• Warrington South: Labour: Nick Bent; UK Independence Party: James Ashington; Liberal Democrat: Jo Crotty; Green: Steph Davies; Conservative: David Mowat
• Halton: Green: Jim Craig; Liberal Democrat: Frank Harasiwka; Conservative: Ben Jones; UK Independence Party: John Moore; British National Party: Andy Taylor; Labour: Derek Twigg