The parliament (Seimas) has 141 members that are elected for a 4-year term. About half of the members are elected in single constituencies (71), and the other half (70) are elected in the nationwide vote by party lists. A party must receive at least 5% of the national vote to be represented in the Seimas.

Since 1991, Lithuanian voters have shifted from right to left and back again, swinging between the Conservatives, led by Vytautas Landsbergis (now headed by Andrius Kubilius), and the Labor (former communist) Party, led by former president Algirdas Brazauskas. This pattern was broken in the October 2000 elections when the Liberal Union and New Union parties won the most votes and were able to form a centrist ruling coalition with minor partners. President Adamkus played a key role in bringing the new centrist parties together. The leader of the center-left New Union (also known as the Social Liberal party), Arturas Paulauskas, became the Chairman of the Seimas. The then-government of liberal Rolandas Paksas got off to a rocky start and collapsed within 7 months. In July 2001, the center-left New Union Party forged an alliance with the left-wing Social Democratic Party and formed a new cabinet under former President Algirdas Brazauskas.

In January 2003, former Prime Minister and Liberal Union Party leader Rolandas Paksas defeated incumbent president Valdas Adamkus in a runoff presidential election. In December 2003, an ad hoc parliamentary commission found that President Paksas' vulnerability to influence constituted a threat to national security. On April 7, 2004, parliament removed President Paksas from office. Parliamentary Speaker Arturas Paulauskas became acting President. Valdas Adamkus won the second round of presidential elections in June 2004 and was sworn in as President on July 12, 2004. The first round of parliamentary elections was held October 10, 2004 and a second round was held October 24, 2004. A new government, led by Prime Minister Algirdas Brazauskas, took office on December 14, 2004. On April 11, 2006, Parliamentary Speaker Paulauskas was removed from his position following a vote of no-confidence. That same day, Paulauskas announced the withdrawal of his New Union party from the ruling coalition, including Foreign Minister Antanas Valionis and Social Welfare and Labor Minister Vilija Blinkeviciute.

Lithuania officially became a member of the North Atlantic Treaty Organization on March 29, 2004 after depositing its instruments of treaty ratification in Washington, DC. Lithuania joined the European Union on May 1, 2004.

Lithuania maintains an embassy in the United States, temporarily located at 4590 MacArthur Blvd, Suite 200, Washington, DC, 20007, tel: (202) 234-5860.