The Everton shot-stopper, who kept 12 clean sheets for the club last season in arguably his finest campaign at Goodison Park, was expected to battle it out with fellow Premier League keeper Brad Guzan.
However, with just three weeks to go until the World Cup, Klinsmann has described Howard as being one of the top five players in his position on the planet.
"Tim is important for us, because we have to figure out a couple of pieces still in the backline," the USA manager is quoted as saying by FourFourTwo. "I think there is something special waiting for Tim [at the World Cup], that he hopefully makes that his special moment.
"He, I think, was in the top three of the Premier League this year, and I look at him as the top five in the world, and that is kind of a moment to catch, so make that World Cup your World Cup.
"We see them a bit closer every day, in scrimmages and training exercises, we see little things that add up, so it gives us more and more information."
The United States get their tournament underway when they face Ghana on June 16.