Political parties and outside groups have already spent large sums in Indiana's Senate race, and voters can expect to see a surge in the last two weeks of the campaign.Republican Richard Mourdock holds a huge lead over Democrat Joe Donnelly in fundraising, and conservative Super PACs have been running ads. But Democrats are planning to pump additional cash into the race as well.From Politico: Democratic groups have booked over $1.6 million in Indiana airtime for the next—and penultimate—week of the state's Senate race, according to a Democratic source. (SNIP) That's a heavy, ongoing investment in a race that Democrats have managed—against their own expectations—to keep close in the home stretch. Morning Score reported today on a poll taken for Democratic nominee Joe Donnelly that showed the race between him and Republican Richard Mourdock still too close to call.As WFPL has previously reported, a number of liberal groups, led by Senate Majority Leader Harry Reid's Majority PAC, have been running ads against Mourdock for the past several weeks.