Tick tock? Rudy Giuliani told Politico yesterday that Robert Mueller has sensed time running out on his special counsel probe into alleged Russian collusion in the 2016 election. Mueller’s probe has no official clock, but the goodwill of Americans might be running low. A new poll from CBS News shows a majority of Americans now believe that the Mueller probe is primarily motivated by politics — although they also want to see it concluded properly.

A year into the special counsel investigation into Russian involvement in the 2016 elections, a slight majority of Americans thinks the investigation is politically motivated. Fifty-three percent say so, while 44 percent think the investigation is justified. …

The shift reveals a hardening stance among Republicans, who are now even more critical of the investigation. While a large majority of Republicans has always seen the investigation as politically motivated, the percentage that thinks so has risen seven points since December. There is an even larger shift when it comes to whether Republicans think Mr. Trump should cooperate with the special counsel. In January, 73 percent said he should cooperate, but now just 53 percent do.

It’s not all about Republicans, though. CBS doesn’t provide the crosstabs on this poll, but they do break out the main question by political affiliation. Among independents — who make up almost half the sample, by the way — 54% believe that the probe is politically motivated, as opposed to only 42% who think it’s justified. And even a substantial number of Democrats (23%) think Mueller’s probe is more about politics than legitimate legal issues.

Republicans do find themselves more isolated when it comes to options. Two-thirds want Congress to intercede to stop it (68/29), although it’s far from clear that Congress has the power to do so, given that the special counsel answers to the Department of Justice and the executive branch. Ninety percent of Democrats and 65% of independents want Congress to stay out of it. As noted in the CBS report, 53% of Republicans want Trump to cooperate with Mueller, but that goes up to 91% among Democrats and 76% among independents. That likely comes from a commitment to the rule of law among the majority of Republicans as well as independents, and certainly among many Democrats who feel that way, even if it’s not a sole motivating factor.

The erosion in Mueller’s standing may matter in terms of Trump’s reactions. The next big move for Mueller will be whether to subpoena Trump, a move with all sorts of political as well as legal ramifications. It might trigger even more erosion in the standing for the probe, especially if Trump tried to arrange a written questionnaire as an option. The failure to produce any indictments, so far, on the core charge is going to make a subpoena look like a fishing expedition whether it is or not. That will reduce the credibility of any report from Mueller when this probe finally ends.

With all that said, though, how much does polling matter to Mueller? Best guess: as much as it matters to Trump, or perhaps even less.  Mueller’s not running for office after this, and he can retire from public life in relative peace and quiet if he so chooses. Special counsels get appointed to ignore these kinds of political pressures, at least in theory, even if people don’t believe it in practice.