"consider decisive" is a correct and usable part of a sentence in written English.
You can use it when you need to demonstrate that a certain opinion or course of action is considered to be very important or that it will lead to an irreversible outcome. For example: "After hours of deliberation, the jurors considered the verdict to be decisive."
This is clearly not the place to gauge the last-minute mood swings of a state that many consider decisive.
If Mr. Gore and Mr. Bush are unable to agree on what they would consider decisive, Professor Greenstein said, it might be wise to name some mediator or mediating body.
His imagined world is clearly linked to the very real history of twentieth-century Europe, but it is made strange, and somehow universalized, by the withholding of detail we would ordinarily consider decisive.
While business angels consider decisive the interest of potential consumers for the product, this aspect is deemed less relevant by the entrepreneur.
In particular, while business angels consider decisive the information regarding the prospective profitability of an innovative project, innovator entrepreneurs assign a significant but not decisive importance to such information.
Nor should doctors' expert testimony, which is subject to error, be considered decisive.
In 1996, the vice president's support of the welfare-reform bill was considered decisive.
Those counties, which went strongly for John McCain in 2008, are considered decisive swing counties, Ms. Parry said.
But at the time, it was the last-minute support of Senator Bob Kerrey, Democrat of Nebraska, that was considered decisive.
You almost never get that clear a test of rival economic views, and the results should be considered decisive.
It gave comparatively little emphasis on granular data about trends among Afghans themselves, which at the time the coterie of counterinsurgents around McChrystal considered decisive.
