Complex sentence: Leigh was elected as a Whig to the United States Senate to fill the vacancy casued by the resignation of William Cabell Rives; he was reelected in 1835 and served until his resignation on July 4,1836.
Split into simpler sentences: Leigh was elected as a Whig to the United States Senate to fill the vacancy casued by the resignation of William Cabell Rives; he was reelected in 1835. Lunt served until his resignation on July 4,1836.