Carter also attempted an overhaul of the tax system, but Congress rejected the idea in favor of tax cuts. Carter's popularity was hampered throughout 1980 because of the difficulty in ending the hostage crisis in Iran. It was also hampered because the Soviet invasion of Afghanistan led him to reinstate draft registration, boycott the summer Olympics in Moscow, and cut domestic spending in favor of military spending. In the November 4, 1980 election, Carter was defeated by Ronald Reagan. On January 20, 1981, just minutes after Carter left office, Iran released the hostages. Since leaving the presidency, Carter has continued the work that stood out during his presidency, acting as a mediator to help bring about peaceful settlements to disputes throughout the world.