You may have thought that stanch meant to stop the flow (usually of blood), and that staunch is what described an ardent supporter (often of a political cause). And you would be right, on paper.
To stanch the rhetorical bleeding:
The federal Liberal government says it will lower the small business tax rate to 10 per cent in January and to nine per cent in 2019, the start of a week-long effort to stanch the bleeding from a self-inflicted political wound. – The Canadian Press
To stanch a meltdown:
Dudley was a principal player in Fed decisions concerning the demise of Lehman Brothers, AIG and Bear Stearns, along with emergency measures taken by the central bank to stanch a meltdown in the financial system. – CNBC
A staunch feminist disappointing her friends:
Friends who described Hofmeister as a staunch feminist, generous friend and promoter of young professional women, say they are disappointed that she has become the public “apologist” for Weinstein. – PageSix
There are clear differences in meaning. We run into a problem when it comes to pronunciation. It may not be self-evident, but stanch and staunch are the same word. We need to hit the dictionaries for this one. We found the following on this excellent page in Collins English Dictionary:
Stanch in American English
(stɑntʃ; stänch; stæntʃ; stanch; stɔntʃ; stônch)
Stanch in British English
(stɑːntʃ) or staunch (stɔːntʃ)
As you can see by the intimidating vocal spellings, eight (8) different pronunciations of stanch are offered; five of these are accompanied by brief audible recordings. Some of them sound like staunch.
Staunch
(stȯnch; stänch)
Make that nine (9) possible pronunciations.
. . .
Stanch made it as the word of the day in Merriam-Webster on 10/07/2009. Here is the podcast (did podcasts exist in 2009?):