Both of these events would have nothing to do with popular opinion and how Lend-Lease was sold to the public in late 1940 and early 1941. Lend-Lease was sold as 'Britain is small, weak, and brave. they desperately need American Help, because Britain is America's front porch. If they go down, we're next!' and 'We'll let the neighbor borrow a hose to put out a fire'
If Britain repulsed an invasion in 1940, the response back to that would be 'What do you mean "they need our help?" They kicked Hitler's tail all by themselves, No need to give them stuff!' Without the popular support, it won't pass. If Lend Lease falls to pass, it won't be there for stuff to start getting funneled to Russia when that war starts a few months later, and Britain will start havinmg trouble paying for its orders from US factories