Table:
text: United States House of Representatives elections, 1868
Ohio
Ohio
District Incumbent Party First_elected Result_
Ohio 12 Philadelph Van Trump Democratic 1866 Re-elected
Ohio 13 Columbus Delano Republican 1866 Retired Democratic gain
Ohio 14 Martin Welker Republican 1864 Re-elected
Ohio 15 Tobias A. Plants Republican 1864 Retired Republican hold
Ohio 16 John Bingham Republican 1864 Re-elected
Ohio 17 Ephraim R. Eckley Republican 1862 Retired Republican hold
Ohio 18 Rufus P. Spalding Republican 1862 Retired Republican hold
Ohio 19 James A. Garfield Republican 1862 Re-elected

Question: Which party is Tobias A. Plants the incumbent in the United States House of Representatives election, 1868 ?