AP Photo/Andrew Harnik
"Not particular," he said when asked by Business Insider following a breakfast for the Pennsylvania delegation in Cleveland, which he spoke at.
Shuster, a Trump supporter, added: "Again, Mr. Trump has been talking about transportation and infrastructure. A couple weeks ago he said he's going to be the greatest infrastructure president in the nation's history."
Last month, while delivering an attack on presumptive Democratic nominee Hillary Clinton, Trump vowed that he would "build the greatest infrastructure on the planet earth - the roads and railways and airports of tomorrow."
"When I see the crumbling roads and bridges, or the dilapidated airports or the factories moving overseas to Mexico, or to other countries for that matter, I know these problems can all be fixed, but not by Hillary Clinton," Trump said. "Only by me."
He said his real estate experience makes him more capable of rebuilding the country's aging infrastructure, but Trump has offered few hints as to what he'd do.
"Construction is what I know," Trump said. "Nobody knows it better."
Shuster called Trump's claim that he'd be the greatest infrastructure president a "tall order."
"That's a tall order because Abraham Lincoln was an infrastructure president," he said. "Teddy Roosevelt was an infrastructure president. The Panama canal. And Eisenhower. All Republican presidents. Infrastructure is a Republican issue, but over the year we've lost. We've got to get back to figuring out how to build out and rebuild our national transportation. It's essential to having a strong economy."