Across the political spectrum, from right to left and in the middle, Americans have become more doctrinaire and ideological in their political views, according to a major new study by the Pew Research Center.

“Staunch Conservatives” and “Solid Liberals,” two groups identified in the study with strong allegiance to the Republican and Democratic parties, are more ideologically consistent internally while sharing almost nothing in common with one another on major political issues. Those findings are emblematic of the deep polarization that now shapes American politics.

Among the increasingly growing segment of Americans who identify with neither party and call themselves independents, there are fewer moderates. Many in the “middle” hold strong, ideological views. The study concluded that three groups in the center of the Pew typology “have very little in common, aside from their avoidance of partisan labels.”

“What we see is a much bigger and increasingly diverse middle,” said Andrew Kohut, president of the Pew center. “What’s striking about it is that they’re not so moderate. People in the middle have some strong, well-defined ideological points of view.”

The Pew study offers a political typology of the nation. It is the fifth such study since Pew began the project in 1987 and, as with past studies, provides a wealth of data and insights into the state of politics. The Pew Center breaks down the current electorate into eight politically engaged groups, along with a ninth that is largely disengaged, based on their party identification, values and attitudes on major issues.

To underscore the diversity of views among those in the middle of the typology, the study points to what it calls Libertarians and New Coalition Democrats. Those who populate these groups share demographic similarities — including education and affluence — but hold sharply divergent political views, especially on the role of government.

The study highlights fissures that cause tensions within each party’s base. More broadly, the document points at the coming clash in 2012 that will test the staying power of a conservative movement that flexed its muscles in 2010 against the strength of the coalition President Obama assembled when he won the White House in 2008.

Michael Dimock, a Pew Center associate director, pointed to three examples of the larger gulf between the most liberal Democrats and the most conservative Republicans since the last study in 2005.

On the question of whether government should do more to help the needy, even if that means bigger deficits, or whether government can’t afford to provide that assistance, there was a gap of 65 percentage points between the two groups. Six years ago, that gap was 52 points.

On the question of whether corporations make too much profit, the gap today is 64 points compared with 56 six years ago.

The biggest change came on the question of whether government is almost always wasteful and inefficient. Six years ago the gap was 20 points, and today it’s 68 points. Dimock cautioned that part of the reason the gap is much larger now is that conservatives were less critical of government when Republicans controlled the White House and the Congress.

When the Pew center last undertook a mapping of the electorate, foreign policy represented the major division between Republicans and Democrats. Today, many of those differences still exist, but foreign policy issues have faded in significance. (The study was completed before the killing of Osama bin Laden on Sunday.)

Today, the most significant divisions that shape the electorate are on the size and scope of government and on Obama himself.

“Views about government have become the big divider,” Kohut said. “But you could add to that … views about Obama are the big divider.”

He added that the reaction to Obama’s presidency has been the inverse of what he expected. “He did just the opposite of what I expected. He didn’t galvanize strong support on the Democratic side,” Kohut said. “He got the conservatives’ and Republicans’ blood flowing.”

In contrast to the 2005 study, Pew categorized Republicans into just two groups this year: Staunch Conservatives and Main Street Republicans. In part, the authors said, that reflects the consolidation of economic and social conservatives into one bloc who share deeply conservative views on almost all issues. Gone is the group known as the Pro-Government Conservatives in the previous study.

Kohut said the groupings also reflect the fact that the Republican base has shrunk since 2005. At the same time, however, there are people who do not identify with the Republican Party who nonetheless hold conservative views, particularly on issues related to the economy and government, who were part of the Republican coalition in 2010. Those include the Libertarians.

In addition to the two Republican groups, Pew identified three Democratic groups and three groups not affiliated with either party. As a practical matter, however, the eight groups have divided evenly between Democratic and Republican candidates in their voting behavior in the past two elections.

Here are the groups and their major characteristics:

Staunch Conservatives: Extremely partisan Republicans, these voters pay close attention to politics, are strong supporters of the tea party movement and even stronger opponents of the president. They favor limited government and a strong defense. They tend to be older, primarily white and about 56 percent are male. More than any other group, they watch Glenn Beck and listen to Rush Limbaugh.

Main Street Republicans: In contrast to the Staunch Conservatives, these Republicans are more skeptical of business and more supportive of government regulation of the environment. Only a third say most corporations make a fair and reasonable profit, compared with three in four among the Staunch Conservatives. But on most social and fiscal issues, they too are strong conservatives and are highly critical of big government. Two-thirds live in the South.

Libertarians: The first of three non-aligned groups, Libertarians are nonetheless Republican-leaning. They are conservative on fiscal issues and very critical of government. But they are moderate on social issues. Just 19 percent say homosexuality should be discouraged by society, well below the view of the overall population. They tend to be well educated and affluent but attend church less frequently than the those in the Republican groups.

Disaffecteds: The Pew study calls this group “the most financially stressed” of the eight groups. Half say their households are struggling and more than two in three of their households have gone through a bout of unemployment in the past year. They see government as wasteful and are skeptical that regulation does much good. Four in 10 did not vote in 2010.

Post-Moderns: This is another group not tied to either party. These voters were strong supporters of Obama in 2008 but turned out in lower numbers in 2010. They are younger than other groups and about six in 10 use social networking. Half live on either the West Coast or in the Northeast and a majority live in suburbs. They are liberal on social issues but skeptical of government doing more to help the poor, if that means going into deeper debt.

New Coalition Democrats: One of three Democratic groups, the New Coalition Democrats are the only group with a majority who are minorities. Nearly a third are African Americans and a quarter are Hispanics. Although they are financially stressed, they tend to be more optimistic about the country and their own lives. They believe in government regulation and favor a bigger government providing more services.

Hard-Pressed Democrats: Majority white and about one-third African American, most live in the South or Midwest. Like New Coalition Democrats, they are financially stressed but more cynical about government. They are churchgoers and conservative on social issues. Two-thirds have a high school degree or less. About six in 10 are female, the largest percentage of any group.

Solid Liberals: Like Staunch Conservatives at the other end of the ideological spectrum, they are highly engaged. They hold strong liberal views virtually across the full range of issues. They tend to be less religious than many other groups. Like Post-Moderns, they are clustered on the East and West Coasts and watch Fox News less than any other group. Half hold college degrees and a quarter hold post-graduate degrees.