This chart was made from a recent Rasmussen Poll -- done on August 11th and 12th of a random national sample of 1,000 likely voters, and has a margin of error of about 3 points.
It shows that 42% of Americans think the United States and its allies are losing the "war on terror", while only 25% now think we are winning it -- a 17 point gap. I don't agree, especially if it's muslim terrorists that you are talking about (and sadly, that's what most Americans think of when you talk about terrorists). I think we could do a little better job of watching right-wing "christian" terrorists in this country, but in general, our law enforcement has done a very good job of stopping terrorism in this country. The only exception would be the unplanned "lone wolf" shooters -- something it is nearly impossible to stop, even in a police state.
I think this attitude that we are losing the war against terrorism comes from most people misunderstanding just what the war on terrorism is. That combine the effort to stop terrorists and the religious civil war in the Mideast (particularly in Syria and Iraq), treating the two as if they were the same thing. They are not.
The war against ISIS in the Mideast is not a war on terror. It is a religious civil war between radical sunni muslims and shiite muslims -- with most muslims stuck in the middle, just wanting it to stop. We shouldn't even be participating in it. It should be decided (and fought) by the nations in the Middle East. And it really doesn't matter who wins it, as far as terrorism is concerned. Do you really think if ISIS (and al-Queda and others) are defeated in that war that terrorism will cease?
Of course it won't. The terrorists didn't need a country of their own to attack this country on 9-11, and if they fail to create a country of their own, that won't stop them from planning terrorist attacks on this country (and the West in general). The only way to stop real terrorism is through capable diplomacy, good intelligence, and a concerted effort by law enforcement.
We are winning the war against terrorists. What we are not winning is our involvement in the nasty religious civil war in the Middle East -- and that is a war we cannot win, and shouldn't even be involved in. All we can do there is create more terrorists with our "collateral damage" (killing of innocent civilians). And we shouldn't forget that most muslims in that part of the world see our involvement there as another crusade of christians against muslims.