The Northern Ireland Secretary has defended investigating the possibility of building a bridge or tunnel to Scotland.
Last month it emerged that such a project between Larne and Portpatrick would cost billions of pounds.
A feasibility study led by Network Rail chairman Sir Peter Hendy found that a bridge would cost an estimated £335 billion, while a tunnel would be around £209 billion.
Mr Johnson had previously expressed his enthusiasm for the proposal.
In the House of Commons on Wednesday, Brandon Lewis defended Mr Johnson for commissioning the research.
He was questioned about the proposal by SNP MP Kirsten Oswald (East Renfrewshire).
Mr Lewis told MPs: “I feel sorry for her – she should think bigger and better and be more optimistic about the future of the United Kingdom.
“I think it is absolutely right that we look at the things that we can do for our country to improve.
“If you don’t look at those things then you’ll never achieve anything exciting that can drive our economy.”
A bridge or tunnel between Northern Ireland and Scotland would likely be the longest structure of their kind ever build, and take almost 30 years to complete.
The project would face challenges, including contending with Beaufort’s Dyke – an underwater trench on the most direct route where a million tonnes of unexploded munitions were dumped between the First World War and the 1970s.