Unlike Hillary Rodham Clinton, rival Barack Obama planned for the long haul.

Clinton hinged her whole campaign on an early knockout blow on Super Tuesday, while Obama’s staff researched congressional districts in states with primaries that were months away. What they found were opportunities to win delegates, even in states they would eventually lose.

Obama’s campaign mastered some of the most arcane rules in politics, and then used them to foil a front-runner who seemed to have every advantage — money, fame and a husband who had essentially run the Democratic Party for eight years as president.

“Without a doubt, their understanding of the nominating process was one of the keys to their success,” said Tad Devine, a Democratic strategist not aligned with either candidate. “They understood the nuances of it and approached it at a strategic level that the Clinton campaign did not.”

What made it especially hard for Clinton to catch up was that Obama understood and took advantage of a nominating system that emerged from the 1970s and ’80s, when the party struggled to find a balance between party insiders and its rank-and-file voters.

The system is designed to benefit candidates who do well among loyal Democratic constituencies, and none is more loyal than black voters. Obama, who would be the first black candidate nominated by a major political party, has been winning 80 percent to 90 percent of the black vote in most primaries, according to exit polls.