By early 1867, the Russian company administering Alaska teetered on the edge of bankruptcy, and the imperial government in St. Petersburg desperately needed an influx of funds.  Russian officials also worried that the increasing American population in the region would one day lead to calls for annexation by the U.S. government (as occurred decades earlier in Texas).  Another strategic concern was how to defend it during a possible war with Great Britain, Russia's enemy which controlled Canada.  Consequently, the Russian minister to the United States, Baron Edouard de Stoeckl, contacted Secretary Seward in March 1867 with an offer to sell Alaska.

When the opportunity presented itself, President Johnson was enmeshed in a bitter struggle with Congress over Reconstruction policy.  Seward, as well, had alienated most of his Republican colleagues by siding with Johnson.  Both men hoped that such a diplomatic coup would enhance their political prestige by diverting attention from domestic matters.  National interest, however, was their overriding motivation.  The great land mass, jutting well into the Pacific Ocean near Asia, offered numerous economic and strategic benefits.

Seward and Stoeckle quickly negotiated a treaty for the United States to buy Alaska for $7,000,000 in gold. Seward hoped to gain Senate approval before the Congressional session ended, and secured the president’s approval, but the Russians raised additional issues and upped the ante by $200,000. By this time, Congress had adjourned, so President Johnson called the Senate into special session on April 1, 1867.

Some of the Radical Republican press, especially the New York Tribune, mocked the Alaskan purchase as "Seward's Folly," "Johnson's Polar Bear Garden," "Walrussia," or "Russian Fairy Land" (as in this cartoon). Most newspapers, though, endorsed the treaty as advantageous for the United States.  To overcome personal animosity to the president and secretary of state, Seward waged an intensive war of propaganda and lobbying.  The effort received a boost from the support of Congressman Thaddeus Stevens of Pennsylvania, a leading Radical Republican opponent of Johnson.  

The decisive factor was winning the approval of Senator Charles Sumner of Massachusetts, chairman of the Foreign Relations Committee.  In addition to his standing as a prominent Radical, many Republican senators followed his lead (at this time) on foreign policy issues.  Like Seward, Sumner believed that the purchase of Alaska would expedite the withdrawal of Britain from Canada and the dominion's ultimate union with the United States.  (Britain, too, envisioned and feared this scenario.)  On April 9, the Senate voted in favor of the treaty, 37-2.

After Congress convened the next year, trouble arose in the House over the treaty.  In March 1868, Republican congressmen sought to embarrass President Johnson further by postponing an appropriations vote for two months until after the impeachment process against him was completed.  (The treaty stipulated payment to Russia by April 20, 1868.)  Another problem was the demand by Congressman Benjamin Butler of Massachusetts that a financial claim against Russia by an American arms merchant be settled before the House voted on the treaty funds.