The emphasis by Hillary Rodham Clinton and Bernie Sanders on raising money directly for their campaigns has helped them amass large donor pools critical to generating the estimated $1 billion each party’s candidate will need to raise by Election Day.

While GOP candidates put an intense focus early in the year on raising huge sums for independent groups, many have had less success in attracting smaller donations that are the lifeblood of campaign operations, campaign finance reports filed Thursday show…

“You could have this big super PAC, but if you have limited momentum and limited money to keep the campaign going, it’s like the guy at the top of Mount Everest with two broken legs and an extra oxygen tank,” said Republican strategist Matthew Dowd. “You’re living longer, but you’re not going anywhere.”