"The most troublesome task of a reform President," wrote Henry Adams, is "bringing the Senate back to decency." Adams was writing about the presidency of Ulysses S. Grant, which began with an Obamaesque promise of national reconciliation and reform but was dragged into scandal by the senatorial kleptocrats of the day.

The Senate has changed since then -- its members are elected now, though no less likely to be millionaires -- but it's still true that the Senate is where ambitious presidencies die. Dozens of subtle explanations are offered for the early failures of the Clinton administration -- from the early missteps on gays in the military to the closed planning process on health care -- but they are as nothing next to the banal fact, proclaimed almost daily on the Senate floor by then Minority Leader Bob Dole, that, "you need 60 votes to do anything around here."

In addition to the right of unlimited debate, which in turn leads to the 60-vote requirement to overcome a filibuster, the Senate is intentionally unrepresentative and its members vain, prickly, and aged (a senator today is more likely to be 75-plus than under 50). This leads to occasional calls for reform, from elimination of the filibuster to the complete abolition of the institution.

I should admit here that I love the Senate, even its anti-majoritarian and unbounded quality, its free play of antique egos, its cluttered toolbox of little-used procedures. So I resist such calls for reform. But they're academic, since the Senate will remain the Senate, and our problems can't wait for a constitutional convention.

Still, some presidents master the Senate, while others, like Bill Clinton or Jimmy Carter, do not. While it's widely believed that governors make better candidates for president than senators do -- since governors can speak in a language of action and achievement, rather than John Kerry's "I was among the first to cosponsor..." -- we are fortunate that the next president, if a Democrat, will have four or eight years of familiarity with the institution. At least he or she will recognize the troublesome task ahead.

The Democrat before Carter, Lyndon Johnson, will always be the model for mastery of the Senate, both from within and from the White House. Johnson's genius was for pure retail politics, understanding the particular motives and foibles of every member in order to build a cross-party coalition resilient enough to outmaneuver the cross-party coalition opposed to civil rights and Medicare.

Ronald Reagan mastered the Senate first by remaking it -- bringing with him 12 new Republican senators, most of them conservatives -- but his most notable innovation was effectively changing the rules to create what's now sometimes called "the 50-vote Senate." A technical procedure known as "budget reconciliation" was transformed into a mechanism to move sweeping budget cuts through the Senate with limited time for debate, eliminating the possibility of a filibuster.

The current President Bush had a far narrower partisan edge than both Johnson and Clinton but was able to extend the 50-vote Senate well beyond the realm of deficit-reduction, using reconciliation to pass tax cuts and other substantive policies. His allies went even further, using the threatened "nuclear option" of eliminating the filibuster for judicial nominations to force an agreement that made it difficult to block two extremely conservative Supreme Court nominations. Bush's approach has been to seek cross-partisan support last, only after using every institutional power available to force a "take it or leave it" deal on Democrats. Remarkably, he has been able to do almost the same thing since his party lost control of the Senate in 2006.

For voters trying to determine whether the next president will be able to achieve universal health care or end the war in Iraq, the key question is not what the candidates' campaign policy proposals say or how many years of experience they have. It is: Who will be able to "bring the Senate back to decency"? Will the next president, like Reagan, be able to remake the Senate, bringing in new members from states like Colorado and Kentucky to reach an actual progressive majority of 56 or 57? And after getting within range of 60, will he or she be able to make the cross-party alliances to draw a handful of Northeastern or Midwestern Republicans out of the stance of massive resistance that they adopted in 1993? And will he or she be able to be as creative as Reagan or Bush in recognizing that small and subtle institutional changes -- as simple as using a rule that?s been forgotten -- can turn the power of the Senate from obstruction to a force for positive change?