A congressional committee on Wednesday will grill Lois Lerner, head of the IRS' tax-exempt division, about her role in the agency's targeting of conservative groups, ensuring that the story will remain front and center in Washington and in the news.

Republicans have sought to link President Obama to that scandal, as well as to ongoing controversies about Benghazi and the Justice Department's seizure of reporters' phone records. Yet despite those efforts, one question remains: What is any of it accomplishing?

Though the supposed scandals have bounced around for weeks now, they don't appear to be doing any real damage to the president, and polls have shown the public eager for Congress to move on to other matters. That Republicans continue to make their case to apparently deaf ears has some asking if the party is blindly focusing on the president at the expense of real issues — and its own beleaguered standing with the American public.

Writing in National Journal, Charlie Cook argues that congressional Republicans are making the same mistake the party made in 1998 when it used the Lewinsky scandal as a cudgel against President Clinton, yet never won over the American public.

"The conservative echo machine had worked itself into such a frenzy, the GOP didn't realize that the outrage was largely confined to the ranks of those who never voted for Clinton anyway," he says.

More from Cook:

Republicans and conservatives who are so consumed by these "scandals" should ask themselves why, despite wall-to-wall media attention and the constant focus inside the Beltway — some are even talking about grounds for impeachment — Obama’s job-approval needle hasn't moved. The CNN/ORC poll suggests that people are aware of and watching the news, but they aren’t reacting, at least not yet. Clearly Republicans hope the public will begin to respond. But at what point do they decide that maybe voters might be more interested in other issues or worries than about politicians on one side pointing fingers and throwing allegations at those on the other side? At what point might the GOP conclude that it is just digging the hole a little deeper? [National Journal]

Indeed, several recent polls seem to indicate that the IRS, Benghazi, and Associated Press trifecta is having little or no impact on public opinion. Obama's approval rating, at 49 percent, has remained unchanged in Gallup's tracking polls; a CNN survey out this week pegged it even higher, at 53 percent, a slight uptick from the network's last survey in April, before all three stories blew up.

Further, a Public Policy Polling survey released last week found that a majority of voters said Congress had better things to do, like pass immigration reform and gun background-check bills, than continue focusing on Benghazi. And that was even after a much-ballyhooed "whistle-blower" hearing into the matter.

"What we're finding after last week's Benghazi hearings is that as angry as Republicans are, most voters think Congress should be focused more on other issues," said PPP President Dean Debnam.

The Washington Post's Greg Sargent flagged yet another poll from that paper on Tuesday in which 60 percent of respondents said Republicans were focusing on issues they felt were unimportant.

"Polls have shown that majorities take the scandals seriously, as well they should, at least in the cases of the IRS story and the Justice Department gathering of media phone records," he says. "But Republicans continue to talk about the scandals in ways that seem mainly tailored to Obama-hating base voters."

Yet Mother Jones' Kevin Drum cautioned against reading too much into these early polls, and especially against making comparisons to the GOP's handling of the Clinton affair in the late '90s. There is still a lot we don't know about the IRS' program and the DOJ's snooping, so it is possible more damaging information could come out.

I'll play devil's advocate here. First, I think 1998 was probably unique: The nature of the scandal was clear to everyone, and a majority of Americans simply didn't think it was very serious. The nature of our current set of contretemps isn't yet clear, and the Post poll makes it plain that most Americans do take them seriously. As we learn more, there's every chance that the public could view them as even more serious. In fact, they probably will. After all, a big pile of scandals in the sixth year of a presidency usually spells trouble. 1998 is the sole exception, and I wouldn't hang too much on it. [Mother Jones]

Returning to that IRS hearing scheduled for Wednesday, Lerner has already said she'll plead the Fifth to avoid answering lawmakers' questions. While that's not in itself an admission of wrongdoing, it could serve to ratchet up criticisms of the president and, perhaps, finally strike a meaningful blow to his approval rating.