Decision 2016: Five States Hold Primaries

A sense of inevitability is growing around both the Donald Trump and Hillary Clinton campaigns, and they could easily build on that momentum this Tuesday. Democratic and Republican voters will cast their primary ballots in five states -- Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island -- where the respective front-runners hold solid leads.

In delegate-rich Pennsylvania, Trump has a 13-point lead over his closest competitor Ted Cruz, while Clinton has a seven-point lead over Bernie Sanders, according to a CBS News Battleground Tracker survey released Sunday. All told, there are 556 delegates at stake --172 for Republicans and 384 for Democrats.

Here's a look at what to watch for on Tuesday:

A clean sweep for Trump?

Trump isn't just leading in Pennsylvania -- polls in all five states show the front-runner comfortably in the lead. Should Trump sweep the five contests on Tuesday, it will add to the growing sense that he's unstoppable. Even in Indiana -- where Cruz may have his last, best chance on May 3 to curtail Trump -- 64 percent of Republican voters say it's "very likely" Trump will be the nominee, the CBS Battleground Tracker shows.

It's already impossible for John Kasich to win the 1,237 delegates needed to win the Republican nomination outright, and after Tuesday, it's likely to be impossible for Cruz as well. Consequently, the two campaigns are now taking the unprecedented step of colluding to stop Trump from reaching that magic number. Kasich is ceding Indiana so that Cruz has a better shot at the state, and a clean sweep for Trump on Tuesday would only up the ante for Cruz in the Hoosier State.

How many delegates for Trump?

If Trump performs performs well Tuesday night, he'll stay on track to win the 1,237 delegates needed to win the Republican nomination outright. Even so, with a current delegate count of 844, Trump won't be able to clinch the nomination until the end of June.

Here's how the delegates from Tuesday night will be allocated: Delaware (with 16 delegates) a winner-take-all state. Maryland (38 delegates) awards delegates on a winner-take-all basis, statewide and by congressional district. Rhode Island (19 delegates) awards its delegates proportionally. Connecticut (with 28 delegates) awards 13 proportionally -- unless someone gets 50 percent of the vote; then, it's winner-take-all. The remaining 15 delegates are awarded on a winner-take-all basis in the state's five congressional districts.

In Pennsylvania (71 delegates total), 17 delegates are winner-take-all, but as many as 54 are unbound. This means those 54 -- three from each congressional district -- can vote for whomever they want. Many of those delegates say they'll back whoever wins his or her district, which bodes well for Trump.

How will Bernie Sanders do?

Hillary Clinton is expected to win all five states on the Democratic side, and a one-state upset by Sanders would do little to change the narrative that the race is all but over.

In Rhode Island, where polls show Clinton with a relatively marginal lead, "unaffiliated" voters are allowed to participate in the Democratic primary, which could help Sanders (it's also the home state of Sanders campaign strategist Tad Devine).

With about 80 percent of the delegates she needs to win the nomination, Clinton is already clearly shifting her focus toward the general election. In Wilmington, Delaware on Monday, she made no mention of Sanders but mocked the GOP front-runner. "Donald Trump says wages are too high," she said. "I have said, come out of those towers named for yourself and actually talk and listen to people."

How does Sanders react if Clinton has a big night?

Clinton's team has been eying April 26 as the date when her delegate lead becomes mathematically insurmountable for Sanders. On Monday, after a particularly contentious few weeks between the Clinton and Sanders campaigns, Clinton released an ad stressing the theme of unity. It began running Monday in the Philadelphia, Pittsburgh, Baltimore and Hartford, Ct., media markets.

It's worth watching whether Sanders pulls backs his attacks on Clinton if she does have a strong night on Tuesday. When asked by NPR if Sanders would ever consider toning down his harsh critiques of the Democratic front-runner, Sanders' adviser Tad Devine said it's a possibility that the Vermont senator could "re-evaluate" after Tuesday.

Even so, don't expect Sanders to drop out any time soon: "We're going to fight his out until the last vote is cast, that is what democracy is about," the candidate said Sunday on CBS' Face the Nation. Sanders has enough enough cash to stay in the race through June 7, regardless of the delegate count.