Yes let's have a Mexican civil war. Carter reluctantly sends US forces to prop up the Mexican government, which only enflames the civil war.
Meanwhile, Comecon is getting rich on jacked up prices for natural resources sold to Europe. The loans to Poland, Romania, etc., are practically forgiven.
The US delays and then cancels the space shuttle program, for cost reasons, during Carter's 2nd term. It never flies. Meanwhile, thanks to the Soviet economic bonanza, the Soviet space program is well-funded and accelerated. The Soviet Buran shuttle flies in 1984.
There is no victory for "marketing ideas" in the 1980s. Socialism (as in was in many countries during the 1940s - 1970s) is seen as the wave of the future.
Governments around the world look at the USSR, and see its economic success, its strong military, and its technological success (e.g. Buran)... and emulate its socialist economic programs (instead of emulating Thatcherism as in OTL).
Of course, in capitalist countries, these "socialist reforms" make things even worse. Economists argue about it, but a common consensus, is that the answer is more "socialist reforms", not less.
With their ideology considered bankrupt by many, the Republican Party's support greatly decreases in the US. In 1984 and 1988, a left-leaning Democrat (who?) is elected President. He sees his job as implementing some "socialist reforms", while retaining the US democratic system, and does so at an accelerating rate through the late 1980s.
In 1989, the President withdraws the last US forces from Mexico.
In 1990, the US's last few remaining European allies are completely economically bankrupt. The Spanish military junta (ruled since the early 1980s) are overthrown in a violent revolution. There are riots in the streets of West Germany.... which is eventually peacefully is absorbed into the GDR. etc.
Communists make a very modest impact in the 1990 US elections, a win 3 seats (2 in California, 1 in Massachusetts) in the House of Representatives.
In 1991, right-wing forces in the US attempt a military coup....