Plan is a noun in that sentence.
Example sentence - My spouse and I met with a financial expert and created a financial plan for our future.
When do you plan to join me? I told him when to arrive.
plan together
The group had to devise a plan, and fast!
The plan was made to succeed.
What a harebrained plan you thought of.
To make this sentence correct you should say "the plan has been met with opposition".
Idea would be a word that would work well for plan.
Even today, the importance of the Anaconda Plan is a matter of debate.
I need to write a business plan to show the bank how the business will operate.
I planned to ride a unicorn to work, but it got stuck in traffic.