With Sens. Hillary Clinton and Barack Obama splitting delegates in primaries and caucuses rather evenly, Pennsylvania Democrats will have a major say in choosing their party’s presidential nominee at the primary election April 22. With large cities bookending vast stretches of farmland, Pennsylvania is a microcosm of the nation and faces many of the same difficulties in health care and farming, among other issues, as the rest of the country. It would be the first time the state plays a serious role in presidential nominating since 1976. Back then, peanut farmer-turned-Georgia-governor Jimmy Carter walloped Sen. Henry “Scoop” Jackson here, knocking him out of the presidential nominating race. Republicans are less likely to have a serious say in picking their nominee because Sen. John McCain established a commanding delegate lead over his top challenger, former Massachusetts Gov. Mitt Romney, in the Super Tuesday primaries and caucuses. But the state could clinch the nomination for Mr. McCain.