A line-item veto would give the President (and future presidents) the power to reduce waste by selectively vetoing provisions in spending bills. At least some state governors already have this power (e.g., the Governor of New York) and have used it to good effect.
The Republican Congress in the 1990s and Bill Clinton together tried to give Clinton and future presidents a line-item veto power. Unfortunately, SCOTUS struck down their efforts in Clinton v. The City of New York and effectively ruled that the only way the president could have a line-item veto is through a constitutional amendment. Hence, this petition is a proposal to amend the Constitution to give presidents that power as another tool to reduce the deficit and wasteful spending.