At first glance, it seems Republicans are verging on a blunder.
With about 90 percent of Americans favoring universal background checks for gun buyers, GOP lawmakers' strong resistance might appear foolhardy.
But these Republicans are making a calculated and probably safe choice, for several reasons. Their districts' all-important GOP primaries are dominated by hard-right activists. The gun lobby is far more organized and fierce than any opposing groups. And Americans' voting habits often reward those who refuse to compromise.
"A small, passionate group of people, no matter how radical or extreme, can be more successful than a reasonable but less passionate majority," said Dan Gross, president of the Brady Center to Prevent Gun Violence. The National Rifle Association's grip on Congress is more myth than reality, he said, but even modest gun control advances remain difficult.
The Senate on Thursday plans to take up legislation to expand background checks to all commercial gun purchases, including those at gun shows. Lukewarm GOP support for a filibuster, which would have killed the measure, was seen as evidence of Republicans' eagerness to appear at least willing to consider new gun laws in the wake of several mass shootings.
Whether any new gun laws can pass the Republican-controlled House, however, is in serious doubt.
The struggle to require criminal background checks for virtually all gun buyers is just one example of congressional dynamics that might appear out of step with national sentiment.
Republicans, especially in the House, adamantly oppose any tax increases, even if they might lead to long-sought reductions in Medicare and Social Security spending, as President Barack Obama offered in his budget Wednesday. This no-new-taxes approach to deficit reduction is at odds with public attitudes, at least at the national level.
A recent CBS News poll found that 58 percent of adult Americans say the best way to reduce the deficit is with a combination of spending cuts and tax increases. One in 3 favors spending cuts alone, and 2 percent favor tax increases only.
An AP-GfK poll in February 2012 found broad support for Obama's "Buffett rule," which would require those earning $1 million or more to pay at least 30 percent of their income in taxes. Nearly two-thirds of Americans supported the idea, while 26 percent opposed it. Congressional Republicans call it a nonstarter.
Partisan gridlock on deficit spending has led to repeated brinksmanship and unorthodox moves, including the year-end "fiscal cliff" showdown and the subsequent "sequestration" spending cuts.
Obama, noting strong congressional resistance to expanded background checks, asked this week if the government is getting out of step with its founding principles.
"If our democracy's working the way it's supposed to," he told Connecticut residents mourning December's elementary school massacre, "and 90 percent of the American people agree on something, in the wake of a tragedy, you'd think this would not be a heavy lift."
Democratic consultant Chris Lehane says Obama has hit a crucial point.
"The political infrastructure is in conflict with our constitutional system of government," which requires compromise between political parties and vested interests, Lehane said. The problem, he said, largely lies with never-ending political campaigns, massive spending by special interests and House districts drawn to be so thoroughly conservative or liberal that they don't reflect national views on key issues.
Polls might show overwhelming nationwide support for expanded gun background checks or for a tax-hikes-plus-spending-cuts approach to deficit reduction, Lehane said. But many lawmakers "are coming from districts where those numbers do not exist."
House Republicans say many of their members fear losing a GOP primary to a hard-right insurgent. Once they are nominated, however, it's almost impossible for them to lose to a Democrat in the general election. For these lawmakers, the safest vote may be against even tiny tax increases or gun control measures, members of Congress say.
This dynamic has pushed the Republican Party farther right, and perhaps farther from mainstream opinion, according to election results, congressional voting patterns and party positions. Democrats, meanwhile, have largely remained the moderately liberal party that Bill Clinton helped forge two decades ago.
In a Washington Post-Kaiser Family Foundation poll last summer, a majority of even the most ardent Democrats said they would prefer that their party's members try to cooperate with Republicans, even if it meant compromising on key issues. Among Republicans, however, most preferred that their partisans stick to their positions rather than try to cooperate across party lines.
Sometimes a well-designed political campaign can convert minority viewpoints to majority positions. A 2012 Minnesota effort to require voters to produce photo identifications appeared overwhelmingly popular at first. But state voters ultimately rejected it.
"A year and a half ago, when this polled at 80 percent, you know it was organizations with networks in communities who jumped in and who started talking to people about the facts," activist Dan McGrath told local reporters.
The U.S. gun lobby takes a different approach, spending enormous resources to keep lawmakers in its corner even when public sentiment is elsewhere.
"The gun lobby is the most powerful special interest in America," said Mike Barnes, a former Democratic congressman from Maryland and former head of the Brady Center. Many Republican lawmakers, he said, "live in total fear that the gun lobby might consider them less than perfect."
The NRA is the best-known of the gun-rights groups, but others make waves, too. The National Association for Gun Rights has aired ads claiming that prominent Republicans — including House Majority Leader Eric Cantor, R-Va. — helped Obama create a national gun registry, an assertion that independent groups call false.
GOP consultant Steve Lombardo said Republicans risk becoming seriously out of step with mainstream opinion.
"The GOP leadership continues to be shackled to old positions that are no longer important to a majority of voters," Lombardo said. "Ninety percent of these Republicans who oppose gun restrictions that are widely supported by most voters come from strongly conservative districts."
"Not enough Republicans come from swing districts," Lombardo said.
Lehane said there have been other times when the nation's political system got out of step with majority opinion. In the 1950s and '60s, he said, support for civil rights legislation was thwarted by an odd-bedfellows Democratic Party heavily influenced by Southern conservatives, some of them segregationists.
The shock of President John F. Kennedy's assassination, plus President Lyndon Johnson's persuasive skills and, ultimately, a political realignment that gave Republicans control of the South, brought U.S. policy more in line with mainstream beliefs, Lehane said.
Now, he said, it may take "some type of significant external event," such as an economic collapse, coupled with effective leaders and a motivated public to put public policy more in sync with public opinion.
But with Republicans and Democrats responding mainly to their ideological bases, Lehane said, "instead of moving to the 50-yard line, both sides are sprinting to their end zones."
AP Director of Polling Jennifer Agiesta and news researcher Monika Mathur contributed to this report.