"challenging proposal" is a correct and usable phrase in written English.
You can use it to refer to a proposal that is difficult or complex in nature. For example, "The mayor presented a challenging proposal that would reduce pollution levels in the city by 20%."
"This proposal is much stricter than the already challenging proposal we received last year from the European Commission," Mr. Zorbas said.
"NASA tried to do the impossible with the most technologically challenging proposal," Ms. Dasch said.
This time, they left the couple with instructions to think things over, review the binder and the fabric and wallpaper swatches, and discuss the most challenging proposal — covering the walls with bold stripes, either by painting or wallpapering them, a project the couple would have to do themselves.
All too often arts organisations, especially small ones, fear resisting or challenging proposals that literally come from another intellectual universe.
How can social enterprises best take advantage of the new 'right to challenge' proposals, for example?
Energy-intensive industries, like power, steel and aluminum, have challenged proposals that would force them to buy many more permits than in the past.
They're skilled at setting up front groups to spread disinformation to challenge proposals...When you see stories about the meetings and how the participants are so concerned about government takeover of our healthcare, they use the very words that were fed to them by the health insurance industry, not realizing that they are unwitting pawns of the industry.
"There are about seven other companies challenging the proposal, but the Citigroup arguments cover most of what the others are saying," he said.
Meanwhile, on Thursday, a state judge is scheduled to hear arguments over whether to dismiss a lawsuit challenging a proposal by Senate Republicans to increase the size of the Senate to 63 seats from 62.
Records show that Mr. Ayers, now a professor of education at the University of Illinois at Chicago, helped write the Challenge proposal.
Part-time posts, research semesters (e.g. for challenging research proposals) and jobs with telestructure amongst others, may correspond to changing life phases and circumstances.
