PEORIA, Ill. – Sen. Ted Cruz (Tex.) urged voters here to cast ballots in the GOP primary – not just for him, but for the delegates to July’s Republican National Convention who support him.

The request underscores a major part of Cruz’s presidential campaign strategy and how it has run its operation in recent days.

As candidates are talking about a brokered convention as a way to stop Donald Trump, the number of delegates a candidate amasses is becoming increasingly important. To win the nomination, a candidate must amass 1,237 delegates, each one awarded when a candidate wins a state or congressional district, depending on the rules of each state. The delegates then vote for a candidate at the party’s nominating convention this summer.

Trump has gobbled up the most delegates so far, holding 469, and Cruz is on his heels with 370. Sen. Marco Rubio (R-Fla.) and Ohio Gov. John Kasich trail, but each man is hoping to win his own state, and the large number of winner-take-all delegates that come with them, on Tuesday.

“Tomorrow is all about delegates,” Cruz told reporters Monday in Decatur, Ill.

Cruz is looking to build on his count and overtake Trump. Over the past week Cruz’s team looked at data practically on a minute-by-minute basis, tailoring campaign stops to where the data showed the candidate had potential to net the most delegates. Rallies were typically not announced until 24 hours before they took place, their location based on numbers-crunching.

Cruz made five stops in Illinois on Monday, each in a different congressional district. Here in Illinois, the winner of the majority vote gets 15 of the state’s 69 delegates, and the rest are divided among the winners of each of its congressional districts; each district gives a candidate three delegates.

“Vote not just for me but also to vote for your delegates to vote for every delegate that’s a delegate for me,” Cruz told a cheering crowd at the Peoria Civic Center.

Cruz also hunted for delegates in Missouri, where he made four stops Saturday. The candidate is addressing the press in different media markets – some of which serve both states – to maximize his reach. In Florida, he held rallies in the population centers of Miami and Orlando, attempting reach the most people in a state that Cruz won’t win, but where he hopes to knock out Rubio.

Conversely, Cruz held only one rally in Ohio, where polling shows him trailing far behind the state’s governor, Kasich, and Trump.

Cruz is a strategist at heart who grows excited talking about the intricacies of campaigning. He has started talking about the convoluted process of amassing delegates on the campaign trail. He tells crowds that he is the only candidate who can beat Trump, breaking down a delegate process that is likely confusing to the average voter and using math to underscore how he believes he can win the nomination.

“There are only two candidates who have any plausible path to amassing 1237 delegates. We have right now 370 delegates, and Donald has 90 more than we do,” Cruz said in Decatur. “Everyone else is way, way, way down.”

The hunt for delegates has been the linchpin of Cruz’s strategy since the inception of his campaign. It is an operation that prides itself on excelling at the nitty-gritty, oftentimes tedious, spadework of campaigning, from securing ballot access to locking down the support of local legislators.

The campaign has gone to far-flung places, sending Cruz to Wyoming in August – a state he ultimately won. It sent an emissary to the Pacific territories who got caught in a typhoon and bought the governor of Guam a birthday cake. Cruz’s father, Rafael, stumped in the U.S. Virgin Islands, meeting with pastors at a church and local officials at a bar on the beach as the sun set over the water.

Cruz netted a delegate in Guam, but the strategy hasn’t always worked as planned. The candidate hoped to win a slate of Southern states March 1, increasing his delegate count and setting up, as he once called it, a “firewall” that would propel him to the nomination. The campaign spent months gathering the support of people on the ground and did two big swings through the region. In the end Trump won almost all of the South.

Cruz's operation also relies heavily on data modeling and polling to try to win voters and figure out where it has the most support, aiding the ability to find delegates. Cruz’s analytics system profiles voters based on psychographic data – if they cast ballots based on fear or hope. The campaign uses that to make entreaties to possible voters and analyzes polling to see where Cruz has advantages.

Cruz told reporters that the campaign appears to have the best shots here in Illinois, in Missouri and in North Carolina, where Cruz appeared at a rally Sunday put on by a super PAC supporting him.

“We are campaigning hard and vigorously in all of them,” he said.