Speakers used to be secure. Not anymore. EPA/SHAWN THEW

There was a time when Speaker of the House was one of the most secure jobs in politics, held by men largely unknown to the American public, who wielded their enormous power behind the scenes until they retired at an advanced age or died in office.

With John Boehner's announcement Friday that he will leave Congress at the end of October, he will become the sixth speaker in a row to effectively be forced to relinquish the gavel.

What is different this time: Where the others over the past 26 years have lost their jobs because of pressures generated by the other party, the Ohio Republican is the first to succumb to a rebellion that built within his own ranks.

That reflects in part the turbulence of politics in this polarized era. Where Democrats held control of the House for 40 years straight before 1994, control of the chamber has turned over twice since then.

The nature of power within the institution has undergone a transformation as well.

The speakership itself no longer wields the influence it once did. Sam Rayburn's old dictum to new members that they should "go along to get along" worked in an era where power within the institution was accumulated over decades, by climbing in seniority through the committee system. Now, even the most junior member can build a national base by stoking ideological fires through mass media.

One of the earliest to understand that was Newt Gingrich, a Republican backbencher from Georgia, who arrived in the House Chamber in 1979 -- as it happens, right around the time the C-Span cameras did.

At a time when Republicans seemed doomed to almost permanent minority, Gingrich and a like-minded band of rebels trained their fire on a Democratic leadership that they branded as corrupt. And in 1989, they claimed their biggest victim: Speaker Jim Wright (D-Tex.), who was forced to resign amid an ethics investigation into his financial dealings.

Wright's successor, Tom Foley (D-Wash.), lost his seat in the 1994 landslide that swept the Republicans into power--the first Speaker since the Civil War-era to be beaten at home. Gingrich became the next speaker, having unseated the amiable Robert Michel (R-Ill.) for the top spot in the House GOP leadership.

Gingrich's tenure lasted fewer than four years. He stepped down in the aftermath of a 1998 midterm election when his party overplayed its hand on President Bill Clinton's impeachment, and unexpectedly lost seats.

He was replaced by the low-key Dennis Hastert (R-Ill.), but an era of political earthquakes was underway.

The Democrats won control of the House back in 2006, bringing in Nancy Pelosi (D-Calif.) as the first woman speaker in history. Many congressional scholars say that she wielded the power of her office more effectively than any speaker of the modern era, using her majority to force through nearly all of President Obama's agenda--most notably, his health care overhaul.

But the backlash to that brought back the Republicans--and Boehner as their speaker.

From the outset, he insisted his would not be a dictatorial style.

"It's not about me," he said shortly after taking the job. "It's not about what I want. What I've committed to, when I became speaker, was to a more open and fair process."

The wave of new GOP members that put Boehner in the speaker's chair had come to Washington with a different kind of mandate. They not only did not revere the old order -- they had contempt for it, having campaigned on promises to shatter it.

And no longer was the speaker's job one that could be done largely out of public view.

As far back as the 1980 presidential campaign, Republicans had run an ad depicting a car running out of gas. The figure at the wheel bore an unmistakable resemblance to then-Speaker Thomas P. (Tip) O’Neill (D-Mass.) During Gingrich's stormy tenure, his staff estimated that his name or image had popped up more than 100,000 times in campaign spots. Pelosi got the same treatment.

“It’s my job to look out over the horizon, make sure I know where we’re going,” Boehner once said when asked to define the role of speaker. “And to make sure the team is working together.”

In other words, a job that may be all but undoable in today's politics.