Sounds easy but they will stop you and repeat “wait, listen...” over and over so they can launch huge payloads of unrelated attacks from all directions.
The most frequently used is that Obama only had two years (2009-2010) and the mess he inherited from Bush's 8 years is so bad it will take him generations to fix, but he is doing all the right things, all the real experts say so. And of course you cant absolutely prove that any long term action, even running up 10s of trillions of debt, is bad for the long term until it is too late.
At this stage I turn off the brain cells and go Hannity and say :"Obama had the congress since 2007. Look at the great economy he inherited from Republicans then and how bad they made it since". Yes, it's a bit silly too but it all they are worth.
Wow, you have a lot of staying power.
They need to quietly, but firmly be brought back to the original discussion. Point out that red herrings and other logical fallacies notwithstanding, they haven’t spoken to the original question. They can’t stand being cornered. If they had a reply to your original argument, they would have used it. You don’t have to accept their unordered load of sidetracks. Tell ‘em to back up the truck, delivery refused:)