As key Senate races get tighter, Republicans" hopes rise Democrats still have an edge in their effort to keep control of the Senate, and they may have been helped Tuesday when Republican candidate Richard Mourdock in Indiana suggested that pregnancies resulting from rape are God's will, possibly damaging his chances to succeed Sen. Richard G. Lugar (R). But both parties agree that many of the most important races have become more competitive in recent days, and their outcomes harder to predict. Senate contests in the presidential battlegrounds of Wisconsin and Virginia, where Democrats had leads in polls a few weeks ago, are now essentially even and could be especially influenced if Romney performs well in those states. Polls show Democratic incumbents in Ohio and Florida still ahead, but those races have tightened as Romney has gained ground in the states. And the Senate races in Connecticut and Pennsylvania, long thought to be safe wins for Democrats, have become real contests. The parties and independent groups are now investing heavily in a remarkably long list of states stretching from Maine to Hawaii. To take control of the Senate, Republicans will need a net gain of four seats if President Obama is reelected, but only three if Romney wins. In that case, Paul Ryan, as Romney's vice president, would become the Senate's tiebreaking vote. A tough road To be sure, the Republican road to the majority remains a high-wire act requiring GOP candidates to catch almost every break in the last days of the campaign. It begins with the 37 Senate Republicans who are not on the ballot this year and the five GOP nominees in conservative states, including Texas and Wyoming, who are running essentially uncontested races. Add Nebraska, where polls show Republican Deb Fischer well ahead of Democratic former senator Bob Kerrey, and before the polls even open on Election Day, Republicans can count on having 43 votes in the Senate next year. Then comes the hard part. To secure a 51-seat majority, Republicans need to win eight of the nine closest races, including protecting four of their seats where contests are hot. Those include the campaigns in deep-blue Massachusetts, where polls show Democrat Elizabeth Warren now ahead of Republican Sen. Scott Brown, and in Nevada, where Sen. Dean Heller (R) is locked in a tough reelection battle against Rep. Shelley Berkley (D). But Romney's rise is giving the GOP new hope. New enthusiasm for the presidential nominee could help in Virginia, Ohio, Florida and Wisconsin. And Romney romps in Republican presidential strongholds such as Montana, now held by Democratic Sen. Jon Tester, and North Dakota, where Democratic Sen. Kent Conrad is retiring, could also boost his party. Both races have been deadlocked for months and have been relatively immune to movements in the presidential contest. But greater excitement about Romney could translate into increased turnout among GOP voters, which in turn could produce meaningful shifts.