stanch, staunch

Stanch or stanch means to stop the flow of a liquid--
Apply pressure to the wound to stanch the blood.
Wrap some duct tape around the pipe to stanch the water.

Staunch or staunch means firm in belief or principle; impervious to outside influence--
He's a staunch conservative; he won't vote for a tax increase.
He is a staunch supporter of the administration.
Staunch, said of a ship or boat, means watertight--
The staunch little craft got through the storm.
Staunch, said of a building or wall, means strong; able to withstand pressure--
The wall is staunch enough to hold back the enemy.

Now that you know that, you can say--
"His staunch defense of the new health program may help to stanch the flow of critical comments."