Howie,
In the end, Reagan had no more effect on the end of the USSR than any of the other cold war Prez. They all continued the path started by Truman, it was going to happen anyway.
Jim, just for the record, Gorbachev was speaking at a session of the Politburo in October 1986, days before he traveled to Reykjavik, Iceland to offer Reagan a groundbreaking disarmament plan, including a 50 percent reduction in nuclear arsenals. If he didn't propose these cuts, Gorbachev told his colleagues:
"We will be pulled into an arms race that is beyond our capabilities, and we will lose it because we are at the limit of our capabilities. … If the new round [of an arms race] begins, the pressures on our economy will be unbelievable."
Fact is after Gorbachev returned to Moscow persuaded that Reagan—who had earlier struck him as a "caveman"—honestly had no intention of launching a first strike against the Soviet Union, and he made this point clear to the Politburo. He meant he could continue with perestroika, which involved not just economic reforms but—as a necessary precondition—massive defense cuts and a transformation of international relations. He needed assurances of external security in order to move forward with this domestic upheaval. Reagan gave him those reassurances. Subsequent conversations between his foreign minister, Edvard Shevardnadze, and Secretary of State George Shultz reinforced his confidence.
Regan did, through his personal diplomacy end the cold war. If Reagan hadn't been president—if Jimmy Carter or Walter Mondale had defeated him or if Reagan had died and George H.W. Bush taken his place—Gorbachev almost certainly would not have received the push or reinforcement that he needed. Those other politicians would have been too traditional, too cautious, to push such radical proposals (zero nukes and SDI) or to take Gorbachev's radicalism for reform at face value. Again to quote him, ...."Therefore the big changes that occurred with me and Reagan had tremendous importance. But also that George H.W. Bush, who succeeded Reagan, decided to continue the process. And in December 1989, at our meeting in Malta, Bush and I declared that we were no longer enemies or adversaries."
That is the moment, according to Gorbachev, the Cold War ended.
On the other hand are you going to give Mr. Obama and Mrs. Clinton credit for restarting it?
How about for support the Muslim Brotherhood/Arab Spring that has left Libya and Syria in chaos (the latter of which spawned the radical group calling itself ISIS), temporarily put Egypt in the hands of the Muslim Brotherhood, and emboldened the invasion of the Ukraine by the Russians?