This time there is a rock-solid excuse, but the sense of a continuing snub is sure to linger: Most members of Congress will not have any opportunity to socialize with the president this year.

Barack and Michelle Obama were not at home Monday evening, when several hundred of their invited guests arrived for the first of the congressional holiday balls. When the festivities began, Air Force One was still en route to South Africa. After the president offers one of the eulogies for Nelson Mandela during Tuesday’s memorial service at a stadium in Johannesburg, the plane will be on its way back during the second black-tie congressional soiree — originally added to the executive mansion’s packed holiday party schedule so every senator and House member might have a shot at a few extra moments with the first couple.

Instead, for several hundred of the less-prominent members — those who aren’t in the leadership and didn’t get a dinner invite during Obama’s long-on-hype-but-short-on-results “charm offensive” this spring — 2013 will end without any presidential face time at all.

The timing of the Obamas’ absence could hardly be helped. And not one lawmaker has been heard begrudging the president’s decision to join about five dozen current heads of state, along with three of his predecessors, at the service for Mandela — who was not only an international icon of racial reconciliation and the first black president of South Africa, but also a personal hero for the president since his college days protesting apartheid.

Still, the host-free holiday parties put an awkward capstone on a particularly bad year for relations between Congress and the president.

For starters, the situation means neither of the annual White House social events to which all members and their spouses are customarily invited will come off as planned. The congressional picnic on the South Lawn, which had provided at least one summertime evening of genuine bipartisan bonhomie for at least three decades, mysteriously disappeared from Obama’s social calendar not once but twice this summer.

At least a few members were willing to buy the initial explanation for the cancellation in June: It was the scheduling office’s oversight during a particularly hectic period, not an overt snub of Congress. Nor was it a way to shave expenses during the sequester, which had already added to the chill in congressional relations when several months’ worth of White House tours for constituents were canceled.

The picnic was eventually rescheduled for Sept. 11 — then called off for good just a week beforehand, after the favorite loud-striped shirts had been ironed and the gingham dresses sent to the cleaners. No reason was given in a perfunctory and unrepentant email to Hill offices, but the message did allow that “the president and Mrs. Obama look forward to welcoming members of Congress and their immediate families at the congressional holiday ball in December.”

Instead, Vice President Joseph R. Biden Jr. and Jill Biden were pressed into service as de facto hosts for both holiday parties this week. And White House spokesman Jay Carney said the decision to hold the balls as planned had been made in consultation with congressional leaders. That created the thinnest of silver linings, at least for House members, because rescheduling for next week would have meant a definitive scrapping of the leadership’s plans to send members home for the year by Friday afternoon.

Still, fairly or not, the latest entertainment awkwardness reinforced a perception that’s widely shared among lawmakers in both parties: This president has never shown very much commitment to making members of the House and Senate feel special, let alone genuinely appreciated, and his overt interest in even going through the motions looks to be quickly disappearing in his second term.

Inviting clusters of lawmakers over to watch a movie or to jawbone on the Truman Balcony, as his predecessors did, is not Obama’s style — something of a surprise, given that he was the first sitting member of Congress elected president since John F. Kennedy. Instead he’s steered almost entirely clear of socializing with his onetime colleagues this year beyond the obligatory state dinner invitation and that handful of meals earlier in the year with clusters of senators.

And Obama’s disinterest in the social lubrication aspect of congressional relations has only compounded his profound second-term challenge with legislative relations. The intense resistance virtually everything he’s proposed has faced from Republicans, especially in the House, might have been softened at some crucial margins by a White House lobbying shop with more heft. But Miguel Rodriguez, who took over the legislative operations ship in January, has been an essentially invisible presence on Capitol Hill.

Having spent the first term as legislative affairs liaison for Secretary of State Hillary Rodham Clinton, for whom he was Senate legislative director, Rodriguez is still not at all known to many of the most influential members — unlike his predecessors Rob Nabors, who had been staff director for House Appropriations, and Phil Schiliro, who was instrumental in steering the health care law to enactment because of his quarter-century of connections as one of the most influential staffers on the Democratic side of the House.

Schiliro’s return next week from his new life in New Mexico, for a several-month assignment helping shield the health care law from election-year legislative brickbats, is an unusually overt move to boost congressional relations that has a pretty good shot at succeeding. In the meantime, and despite the miserable weather, hundreds of spouses have arrived in Washington to join their lawmaker partners in their tuxedos and evening dresses — knowing they won’t get a new picture with the president for their bragging wall but making the most of the fact that they got into the White House even once in 2013.