The United States was proud to play a decisive role, especially in the early days, and then in a supporting capacity.

WHITEHOUSE: President Obama Salutes the People of Libya

To take up this challenge, UNESCO has a decisive role to play.

UNESCO: THEMES

The committee has urged the government to set a deadline for coal-fired power stations to adopt CCS, which it says could play a decisive role in reducing carbon emissions.

BBC: Debate on carbon capture and storage

Both campaigns know that just a single electoral vote could play a decisive role in what's expected to be a historically close race, and that makes what happens in the event of an Electoral College tie all the more intriguing.

CNN: Electoral College tie possible in Obama-Romney race