Shropshire Council leader Peter Nutting said he was “absolutely confident” the dualling of the road between Montford Bridge and Ruabon would go ahead.
Councillor Nutting said he was working with colleagues on the Welsh side of the border on the plans, with the Assembly keen to bring economic benefits to both sides of the border.
He said he was also delighted the full council signed off the government’s £54.4 million funding for the Shrewsbury North West Relief Road last week.
And he said once that had been agreed and work had begun, attention would turn fully to the dualling project.
Councillor Nutting said: “I am absolutely confident that we will get the funding and help that we need to dual it.
“We are working with our colleagues at the Welsh government on this, because the economic benefits would also have a great impact on Wales as well. Having the road dualled there would be ideal for both of us and I am confident that together we can put together a winning case.”
The plans took a major step forward when Councillor Steve Davenport, Shropshire Council’s portfolio holder for highways and transport, gave a speech at Westminster earlier this month attended by transport secretary Chris Grayling and Jesse Norman, under-secretary of state for transport.
Councillor Davenport was speaking at Westminster as part of a visit by the Marches Local Enterprise Partnership, which promotes and supports businesses across the region.
It is the only section of the A5, which runs between London and Holyhead, to be single carriageway.
Figures released last year showed that since 1991 there have been more than 1,785 casualties on the A5 north of Shrewsbury up to the Welsh border at Chirk. At the last count, 1,407 of these were slight, 320 were serious and 58 were fatal.