Meanings of underscores the difficulty in English

Cornyn's opposition underscores the difficulty Obama would face.

His defiant reappearance underscores the difficulty of targeting leaders of militant groups in the lawless tribal belt of Pakistan.

And they won it by the slimmest of margins, which only underscores the difficulty and magnitude of their victories.

The ruling underscores the difficulty faced by some other states and local governments to rein in pension costs for current and retired workers.

The estimate, made by the Finance Ministry, underscores the difficulty of fixing Japan's tattered finances, which are now the worst among major developed nations.