Complex sentence: He lost his re-election campaign in 1900, but won election again in 1902, serving for another three consecutive terms until his resignation on June 17,1909, to take up his seat as a U.S. Senator.
Split into simpler sentences: He lost his re-election campaign in 1900, but won election again in 1902, serving for another three consecutive terms. He resigned his House seat on June 17,1909, to take up his seat as a U.S. Senator.