President Trump’s re-election campaign plans to step up its efforts to capitalize on so-called bundlers, supporters who can raise money from friends and business associates in increments up to $2,800, the legal limit for a level of giving that has lagged in the campaign despite a far more sophisticated fund-raising operation than existed in 2016.

The campaign has excelled at small-dollar fund-raising online and at raising six-figure donations from wealthy individuals and corporations for a joint-effort fund-raising arrangement between the Trump campaign and the Republican National Committee.

But there has been little effort to cultivate bundlers who can gather donations from a network of friends and associates that can go directly to a candidate’s campaign.

Mitt Romney and George W. Bush, who ran for president before legal changes allowed joint committees to accept six-figure checks, were prodigious fund-raisers who tended to their bundling networks, ranking them based on the amount they had raised and rewarding the bundlers with names like “Pioneers” and “Ramblers” and giving them special access at retreats and other events.