The phrase "as the deciding factor" is correct and usable in written English.
It can be used when discussing the element that ultimately influences a decision or outcome in a particular context.
Example: "In the end, it was the cost of the project that served as the deciding factor in our choice of contractor."
Alternatives: "as the key determinant" or "as the crucial element".
That produced an agreement that institutionalized ethnicity as the deciding factor in political and social identity.
Alumni often people of color, LGBTQ, or both frequently cite inclusivity as the deciding factor when they choose to live at Senior House.
Alabama analysts pointed to the persistence of traditional white Southern attitudes on race as the deciding factor in Mr. McCain's strong margin.
But Lee pointed to 3-point shots by the Lakers' role players — including Jordan Farmar, Shannon Brown and Artest — as the deciding factor.
The Christian Democratic Union, a center-right party that won 9percentt of the vote in elections on Friday and Saturday, emerged today as the deciding factor in whether the Czech Government stays to the right or moves left.
To get there, Mr. Christiansen and his fellow committee members decided to use need — which they collectively decided to measure by the percentage of students in the schools receiving free lunches — as the deciding factor.
The Motion Picture Association of America cited "sci-fi action violence" as being the deciding factor.
Somehow, that doesn't strike me as being the deciding factor, especially considering that Apple and Amazon (not to mention Kobo and Barnes and Noble) products have managed to co-exist just fine on Target's shelves for years.
And as much as money may be the deciding factor, he has tried to follow his passion, too.
The word count wasn't the deciding factor as much as what was actually being said.
Design, as much as actual performance, could be the deciding factor in this competition.
