WASHINGTON — Donald Trump needs another big night Tuesday to stay on track to clinch the Republican presidential nomination by the end of the primaries.
Five states are voting. Trump can afford to lose only one.
There are a total of 172 delegates up for grabs. If Trump can win Pennsylvania, Maryland, Connecticut and Delaware, he can walk away with 92. He can pick up even more if things go just right in Pennsylvania's quirky delegate primary.
He can afford to lose Rhode Island because the delegates are awarded proportionally, so even the losers can get delegates.
Trump's path to the nomination is narrow. By no means is it a sure thing. He heads into Tuesday's contests with 845 delegates. That's 392 short of the 1,237 needed to win the Republican nomination.
Trump's rivals, Texas Sen. Ted Cruz and Ohio Gov. John Kasich, cannot win enough delegates in the campaign's home stretch to clinch the nomination. Their only hope is to block him and force a contested national convention in July, with no candidate arriving with a majority.
In their effort to stop Trump, Cruz and Kasich have formed an extraordinary alliance, Kasich has agreed not to campaign in Indiana's May 3 primary, and Cruz has agreed not to campaign in Oregon and New Mexico, which vote later.
Trump can afford to lose Oregon and New Mexico, which award delegates proportionally. Indiana, however, is especially important because the winner can collect all 57 of the state's delegates, or at least a large majority.
Trump needs to win 58 percent of all remaining delegates to reach the magic number by the end of the primaries on June 7.
What follows is not a prediction, but a plausible path for Trump to stay on track Tuesday.
Pennsylvania is the biggest prize, with 71 delegates at stake. But the state's unique ballot could make it hard for anyone to win a big majority.
The statewide winner gets 17 delegates. The other 54 — three from each congressional district — are directly elected by voters. But their names are listed on the ballot with no information about which presidential candidate they support.
These 54 delegates will go to the convention as free agents, free to support the candidate of their choice.
Trump and the other candidates have recruited supporters to run as delegates. But most people will be voting blind, perhaps choosing a local official whose name they recognize.
Let's say Trump wins the 17 statewide delegates, and seven of his supporters are also elected as delegates.
Trump's running total under this scenario: 869 delegates.
Maryland has a total of 38 delegates. The statewide winner gets 14, and the winner of each congressional district gets three.
If Trump can win the state and a majority of the congressional districts, he might pick up 32 delegates.
Trump's running total: 901.
Connecticut has a total of 28 delegates. The statewide winner gets 13 — if he gets more than 50 percent of the vote. Three delegates to go the winner of each congressional district.
The New York real estate mogul needs to win his neighboring state. If he does well, he might get 22 delegates.
Trump's running total: 923.
Rhode Island has 19 delegates. They are awarded proportionally, so even the losers can get some, as long as they get at least 10 percent of the vote.
Trump could lose Rhode Island and still get five delegates.
Trump's running total: 928.
Delaware has 16 delegates and all of them go to the statewide winner, increasing the importance of this small state. If Trump loses Delaware, he has to make up the 16 elsewhere.
If he can win Delaware, he can win a total of 99 delegates in all of Tuesday's states, including the extra ones in Pennsylvania.
Trump's running total: 944.
If Trump can pull off a day like this on Tuesday, he would still need 58 percent of the remaining delegates to reach 1,237 on June 7. Five states vote that day, including California, with 172 delegates at stake.
Trump will have to win big in California to clinch the nomination that day. How big? That depends on how he does in the contests between now and then.
California's delegate rules are similar to those in Connecticut and Maryland. But California is a large and diverse state, with 53 congressional districts.
The statewide winner gets only 13 delegates. The other 159 are awarded according to the results in individual congressional districts. You win a district, you get three delegates.
The more delegates Trump can win before June 7, the more room for error he will have in California.
Follow Stephen Ohlemacher on Twitter at http://twitter.com/stephenatap