WASHINGTON - The blur of Washington news this week - major decisions on voting rights, affirmative action, same-sex marriage and immigration - was a vivid illustration of how Americans are grappling with fundamental social change.

Some of this transition has been underway for decades, notably the efforts by African-Americans to gain equal rights. Some, such as the tide of immigrants from Spanish-speaking countries, has affected the United States over the last several years. Others, such as same-sex marriage, have emerged only recently.

The changes have ignited fierce reactions in the American political system. Each effort to absorb this week's decisions triggered new, often-hostile debates that are likely to define 2014 and 2016 campaigns. "These issues are laden with political consequences," said Andrew Kohut, the founding director of the Pew Research Center.

Perhaps none demonstrates the way these changes tear at the country and its politics as immigration does. The Senate voted Thursday to create a path to citizenship for more than 11 million immigrants now in the country illegally, while further militarizing the U.S.-Mexico border to keep others out. All Democrats in the Senate voted for the overhaul; Republicans split.

Many Republicans see the country changing fast, and are eager to get on the right side of the growing Hispanic population, which helped give President Obama a second term. But those who do may face tough primary challenges from tea-party activists that could divide the party in key states heading into the next several elections. Example A is Sen. Marco Rubio, R-Fla., once a darling of the tea party, whose support of the immigration plan has turned him into a pariah to some conservatives.

Most of his Republican colleagues saw the Senate plan as little more than amnesty, and they were convinced that the public wouldn't buy it.

"Every time I start to talk about immigration at a town meeting, someone stands up and says, 'We need to enforce the laws we have on the books,'" said Sen. Charles Grassley, R-Iowa.

The political passion was less evident on this week's other issues, but it's simmering. The changes in play this week were first evident Monday, when the Supreme Court ruled on a case that involved the University of Texas' admissions policies and signaled that it was skeptical about race-conscious admissions standards.

The next day, the justices struck down a major provision of the Voting Rights Act, a key agent of change since it became law in 1965.

It's been a crucial tool in opening up black participation in Southern politics. Its reach was sweeping, as it led to the election of more black officials, which in turn helped provide better government services in long-neglected minority neighborhoods.

Now, however, the Supreme Court majority said there'd been enough progress over the last half-century that the key section of the law was outdated.

Any fallout might not be felt in coming elections. Because congressional district lines were redrawn after the 2010 census so that most districts are safely Democratic or Republican, the court rulings seem unlikely to spark big changes, at least right now.

The same-sex marriage issue might follow a different scenario. Public opinion is still evolving, but the issue remains politically volatile.

In Virginia, for instance, Attorney General Ken Cuccinelli, the Republican gubernatorial nominee, has been active in opposing same-sex marriage and in efforts to curb gay rights. Democratic nominee Terry McAuliffe praised the Supreme Court ruling.