The Federal Reserve's policy board is expected to embark on fresh monetary easing measures as it meets Wednesday and Thursday to address a weak US economy and stagnant job creation.
But just how far the Federal Open Market committee will go, and what kind of impact it can have, is unclear, analysts said.
After three years trying to get the economy humming following a deep recession, problems outside the Fed's hands, like recession in the eurozone and China's sharp slowdown, are damping its impact.
Also casting dark shadows are the tight presidential election battle and the political stalemate over debt and fiscal policy, which businesses cite as worrisome sources of instability.
Even so, with the newest data on the economy mostly discouraging, and Fed chairman Ben Bernanke strongly in favor of new action, the FOMC is likely to deliver some type of medicine aimed at pushing interest rates lower to encourage borrowing and investment.
That could come in the form of extending its forecast for the period it expects to keep its benchmark rate at the current near-zero level -- essentially a promise that it will not raise rates over the next three years or so.
Or it could come with a third "QE" quantitative easing bond buying program, which aims at lowering long-term rates.
"Recent public comments, as well as the minutes from the last Fed meeting, indicated that if the economy did not begin to meaningfully improve policymakers would be inclined to act more aggressively," said Joseph LaVorgna of Deutsche Bank.
"Last week's data was not encouraging in this regard... which is why we now anticipate quantitative easing measures."
Bernanke's baring of deep worries about the eight-percent-plus level of unemployment in an August 31 speech was the strongest signal so far of the likelihood of the Fed taking new action.
"Growth in recent quarters has been tepid, and so, not surprisingly, we have seen no net improvement in the unemployment rate since January," he said.
"The stagnation of the labor market in particular is a grave concern not only because of the enormous suffering and waste of human talent it entails, but also because persistently high levels of unemployment will wreak structural damage on our economy that could last for many years."
Bernanke's view earned support on Friday when national data for August showed a poor level of jobs created during the month -- only 96,000 -- and also that some 368,000 people gave up searching for jobs and left the labor force.
The dropout level, rather than a surge in people getting jobs, helped push the unemployment rate lower to a deceptive 8.1 percent.
More indicative was that the employment-to-population ratio fell to 58.3 percent, compared with 65 percent-plus before the 2008-2009 recession.
Such numbers shore up Bernanke's view within the 10-member FOMC, which has been divided over whether to take more action in recent months.
With critics saying the Fed's low interest rates are not turning into lending by banks or job-creating investments by companies, Bernanke gave a stiff defense of the two previous QE programs in his August 31 speech.
Such actions "may have raised the level of output by almost three percent and increased private payroll employment by more than two million jobs, relative to what otherwise would have occurred," he argued.
Still, there were doubts about how far the FOMC is ready to go this week, or whether they might just put off the decision until later in the year.
"Markets are seemingly positioned for QE3, yet the latest Fedspeak and recent macroeconomic data do not provide obvious support for additional easing," said economists at BBVA Research.
"The previous FOMC meeting minutes highlighted the intense internal policy debate among committee members, proving that there is still a significant divide in ideology."
John Ryding and Conrad DeQuadros at RDQ Economics said Fed action, whether launching QE3 or extending their commitment to zero-level interest rates into 2015, "will do little, if anything, to boost growth."
"There is no shortage of liquidity in the banking system with reserves at almost $1.5 trillion. There is, however, considerable uncertainty on the outlook for the taxation of labor and capital in 2013, which we think is the major challenge for the economy over the remainder of this year."