The phrase "a more decisive role" is correct and usable in written English.
It can be used when discussing the importance or influence of someone or something in a particular situation or context.
Example: "In the upcoming project, I hope to take on a more decisive role in the decision-making process."
Alternatives: "a greater influential role" or "a stronger leadership role".
But the largely winner-take-all nature of the Electoral College plays a more decisive role than the media in the two-party system.
The U.S. and Europe have to play a more decisive role, they have to provide more resources, because we don't consume the drugs.
In recent months, to take one example, PepsiCo Inc. has talked publicly about playing "a more decisive role" in bringing ready-to-use foods to needy populations.
Although a more decisive role for the Con gress in limiting the power of one man to bring on the final Armageddon is problematical, it demands study and review in the context of current Asian policies.
If the focus of development shifts from mere economic growth to eradicating the widespread poverty, the people as a whole can play a more decisive role, not only in turning the economic fortunes of their countries around but also in enhancing the quality of the environment.
They said it succeeded only in alarming its neighbors and potentially forcing China, which had been trying to play a role of mediation between North Korea and the United States, to take a more decisive role in pressuring its onetime Communist ally.
The structure of government plays a still more decisive role.
He also sought further to downgrade the importance of empirical arguments by suggesting that aesthetic criteria, personal whims and social factors have a far more decisive role in the history of science than rationalist or empiricist historiography would indicate.
While science can typically track down creatures that are hosts to threatening viruses, such human factors as population growth, income inequality, environmental degradation, climate change and even global travel may all play a much more decisive role in unleashing outbreaks of deadly and hard-to-control diseases.
The healthiest good team wins the championship in a typical NFL season, and Raider executive Al LoCasale predicts that injuries will play an even more decisive role this season.
Perhaps the negative feedback of cloud cover has kicked in, dampening global warming, or the ocean absorption of atmospheric heat is playing a new and more decisive role.
