Former House Speaker Tip O'Neill, a Massachusetts Democrat, learned a saying from his father that has since saturated American politics with its blunt, simple truth: “All politics is local.”

House Majority Leader Eric Cantor, contrary to a lot of political commentary, took Tip's mantra to heart, but he did it the wrong way.

He spent roughly $5.2 million over the course of two years, including nearly $1 million from the end of April through Election Day, to run ads and shore up his popularity in Virginia's 7th Congressional District. He visited with constituents at home weekly -- an almost unheard-of level of engagement by a senior House leader, made easier by his district's proximity to Washington. And he faced a largely unknown opponent, Dave Brat, a college professor who had never held elected office and spent just $200,000 during the whole of the election.

Cantor knew he was vulnerable, fought hard — and lost, by 11 points. The outcome was politics at its most local and basic, and yet, its most shocking.

One day later, reporters asked the second-ranking House Republican to explain his stunning defeat.

“I’m going to leave the political analysis to y'all,” Cantor, as relaxed as ever, said repeatedly in response.

Political opportunists in both parties have gleefully accepted that open invitation to fill in the blanks. Long-shot Republican insurgents across the country predicted a wave of fresh momentum for the Tea Party and puffed up their races as “the next Virginia.” Democrats pointed to a Republican Party moving further to the right, no doubt a liability in November. Opponents of immigration reform cheered the victory as a rejection of Cantor's openness to working on that issue.

But the root of Cantor’s downfall might be more clear-cut than that. He understood he had a problem, but he addressed it in a way that created an even bigger one.

Cantor saw a threat early on from conservatives in Virginia who supported a move away from primaries to conventions, which tend to benefit the most ideological among candidates. To quash the move before it grew, Cantor’s network of allies attempted to limit the conservatives sent to the district conventions where such decisions are made.

The interference roused and angered conservative activists in Virginia, and the conflict came to a head at the 7th District convention in May, where Cantor rued the “inaccuracies” being spread about him and was met with resounding boos from a crowd filled with vocal Brat supporters.

“I’m tempted to fight fire with fire,” Cantor responded, “but instead, let me just leave you with some thoughts.”

But some of his thoughts were nevertheless fiery, and Cantor verbally lambasted Brat — drawing further boos. One man stood and gave Cantor two thumbs-down.

“The 7th District convention was something to make all of us worry,” said Connie Buttimer, president of the Susan Allen Republican Women’s Club in Cantor’s district and a Cantor supporter. She recalled activists “who were boisterous, catcalled, and carried on in a very bad manner.”

“I thought that was a scary thing” for Cantor, Buttimer added.

Another House Republican, Speaker John Boehner, faced similar potential pitfalls at home as he ran for re-election in a primary race earlier this year.

When Boehner’s home county sat down to decide whether to endorse him, there was unprecedented, robust support for an alternative. “This is John Boehner’s house!” one supporter yelled out at the meeting — but less than three quarters of the Butler County GOP agreed, an all-time low for Boehner.

Still, Boehner ran the campaign that some party strategists think Cantor should have run — never attacking his opponent or even naming him, while running positive television ads touting his work for Ohio and shoring up support tactfully behind the scenes.

In multiple attack ads, meanwhile, Cantor’s campaign unwittingly introduced his district to Brat, by name, and to his biography — offering an alternative to constituents who might otherwise have thought they didn’t have one.

“They gave me $1 million in name ID and I think that got us going,” Brat told Politico in an interview following his victory.

The ads likely gave a name to, and accelerated, a growing anti-establishment strain in Cantor’s district.

Doug Rogers, chairman of the Republican Orange County Committee and a longtime Cantor supporter, was working the polls Tuesday when he ran into an old acquaintance who had been involved in the committee a few years ago. But now, he was out to support Brat.

“He said he didn’t want to support Eric because he’s the establishment,” Rogers said. He had heard the same argument from other Brat supporters. “I said, ‘You’re trading in the No. 2 person in Congress for a rookie who’s going to have an office in the basement.’ Frankly, they didn’t care.”

If the majority of Cantor’s constituents thought he had lost the pulse of his district, Cantor was adamant the day after the election that, from his end, it just wasn’t the case. He had visited his district every week, he insisted. He had done the legwork.

“I really do believe we did everything we could,” Cantor said. “I just came up short.”