In one four-hour stretch, the nation’s political polarization was on stark display.

Just after 10 o’clock Tuesday morning, the Supreme Court struck down a key provision of the Voting Rights Act. Republicans in several Southern states moved to impose voter identification laws that had been delayed under the law — and blamed by some for helping energize minority communities against the GOP. The court’s decision devastated Democrats.

Hours later, President Barack Obama announced a series of executive actions to combat climate change, dismissively comparing skeptics of global warming to members of the flat-earth society and implementing the sort of ambitious environmental agenda that Democrats cheer even though it helped lead to the party’s losing control of the House in 2010. Republicans cried foul.

More divisive actions were to come Wednesday — the high court’s decisions favoring gay marriage and the Senate’s passage of a sweeping immigration law that many conservatives deride as amnesty. But it’s the earlier moves on voting rights and climate change that reveal the most about how Republicans and Democrats tack toward their core constituencies. That generates a polarized dynamic that has largely deadlocked the federal government, putting into jeopardy its ability to pass a farm bill or a budget — or to raise the debt ceiling and pay the bills it owes.

Analysts say the dysfunction can be blamed on the tendency of political parties that were once coalitions of different political types to sort themselves out by ideological lines. The Pew Research Center for People and the Press reported last year that Americans are more divided along political lines now than at any time since the institute began tracking measures 25 years ago.

"The trend we’ve seen over the last few decades is to have these party bases that are increasingly active in party nominations," said Seth Masket, a political science professor at the University of Denver. Bipartisan, centrist consensus, he said, "is really hard to reach when all these elected officials owe things to these highly partisan people who put them in office."

The past week, Masket said, is "just the result of polarized government."

After Republicans won control of numerous states following the 2010 election, they pushed through new voter identification laws and regulations they said were designed to combat voter fraud. Democrats argued that the efforts were really attempts to suppress the rapidly growing minority vote. Federal courts repeatedly blocked the measures. In the 2012 presidential election, Hispanic and Asian voters backed Obama by a more than 2-1 margin while blacks turned out at a higher rate than whites and supported Obama by more than 9-to-1.

The growing gap between minority voters and the GOP has led to great soul-searching by the Republican Party and a push for more outreach to marginalized communities from the Republican National Committee.

The five-judge majority opinion issued Tuesday by the Supreme Court agreed with longstanding conservative arguments that the 48-year-old Voting Rights Act has led to unfair and outdated standards for Southern states that are far more integrated now than they were in the early 1960s. Texas’ Republican attorney general quickly announced he was reinstating voter identification plans that had been halted by Justice Department voting rights lawsuits. Mississippi’s governor announced that state’s voter identification law would go into effect, and North Carolina Republicans promised to advance one through their statehouse.

Jotaka Eaddy of the NAACP warned Republicans they would face a backlash unless Congress, as the Supreme Court urged, draws up new standards for what states are covered under the law — something that appears unlikely given partisan divisions.

"If Congress fails to act, it will trigger an emboldened electorate," Eaddy said.

Roger Clegg, president of the Center for Equal Opportunity, which supported the Voting Rights Act challenge, said he thinks there will be limited fallout. "Democrats understand they have to be careful challenging commonsensical laws like voter ID, and Republicans have to be careful in explaining these laws are good for everybody," Clegg said.

Obama’s environmental actions are already proving divisive. The president initially hoped to combat climate change through a market-based "cap-and-trade" program, an idea once favored by Republican administrations that would enable polluters to trade credits on an exchange. In 2009, the Democratic-dominated House passed such a proposal, but it died in the Senate. Republicans in 2010 took the seats of coal-country Democrats, and control of the House, partly by campaigning on the issue.

Obama’s announcement Tuesday that he would require new limits on how much carbon dioxide power plants may emit amount to essentially a Plan B on climate change that does not need the approval of a divided Congress. He has been under unrelenting pressure from environmental activists — a key Democratic constituency — to take steps to combat rising temperatures.

Republicans pounced, launching online videos against seven Democrats representing House districts in energy-producing regions and pledging to tie Democratic senators representing Democratic-leaning states to the plan. "This is not a winning issue for them in 2014," said Daniel Scarpinato, a spokesman with the National Republican Congressional Committee.

Darry Sragow, a California-based Democratic consultant who has worked on climate change issues, said Republicans may see a short-term gain, especially because framing the issue as climate change as opposed to jobs or energy security can divide voters. But he argued that the GOP cannot oppose a scientifically supported policy without it taking a toll on its image.

"In the short term they may win some elections," Sragow said. "But it has the Republicans taking a position that, in the long run, is going to be deadly to them."

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