NEW YORK ( TheStreet) -- The time for the world's central banks to live up to the assumptions of additional stimulus that have fueled the rally in stocks this summer is fast approaching.

First up, of course, is the European Central Bank, which reportedly could outline plans for an unlimited bond-buying program on Thursday. On the surface, this proposal resembles the panacea eurozone watchers have been waiting for but the details may tell another story.

The analysts over at Capital Economics were taking a very skeptical view ahead of the announcement. Among the firm's criticisms was the "sterilized" nature of the asset purchases, referring to expectations that the ECB plans to make sure the bond buys have a neutral impact on money supply, thus falling short of "full-blown" quantitative easing, and the fact that the bank is likely to concentrate on bonds with short maturities of less than three years.

Even the "unlimited" nature of the anticipated proposal from ECB President Mario Draghi fails to impress.

"For a start, the lack of a limit on bond buying could simply reflect unwillingness on behalf of the ECB to commit to a specific amount of purchases rather than anything bolder," the firm wrote in commentary on Wednesday, adding later: "Meanwhile, Draghi is likely to restate that the ECB will not act until the EFSF European Financial Stability Facility or ESM European Stability Mechanism have bought bonds, which could be months away. And it seems the Bank's purchases may be conditional on the governments in question meeting economic and fiscal targets -- the Bank could even threaten to stop bond purchases or even sell its existing holdings if governments fail to comply with demands."

And while it seems to be a foregone conclusion that the Federal Reserve will come through with an announcement of QE3 at the central bank's next policy meeting on Sept. 12-13, Deutsche Bank was leaving some room for Ben Bernanke to throw the markets a curve ball.

"We believe there is scope for additional QE, but not necessarily next week," the firm wrote. "The Chairman's comments evaluated the effectiveness of both traditional and non-traditional monetary policy actions over the past five years. Importantly, he noted that both traditional (interest rate cuts) and nontraditional (QE/Twist/language guidance) tools were effective."

There's also some "sell the news" risk out there, at least when it comes to the major U.S. equity averages, which are all sitting on impressive year-to-date gains.

The economic recovery remains slow -- a prerequisite for QE3 -- and corporate profit growth is topping out so there may not be much more room to run once investors get the accommodation they've been craving. Especially when factoring in the uncertainty presented by the presidential election in November and the fiscal cliff.

UBS thinks a pullback for the broad market is in order. The firm reiterated its year-end target of 1375 for the S&P 500 this week, noting the soft data and reduced earnings expectations coming out of second-quarter reporting season as well as its belief that the reality of more quantitative easing won't be enough to support another spike higher.

"While stocks continue to advance on hopes for additional asset purchases, we believe that investors will ultimately be disappointed," the firm said.

Sam Stovall, chief equity strategist at S&P Capital IQ, painted a much more bullish scenario though. He believes the recent pullback from overbought conditions when the S&P 500 reached a multi-year high of 1426 in intraday action on Aug. 21 has set the broad market up nicely for another run to new highs.

"If the pullback is over, we see the S&P 500 breaking to new recovery highs above 1,422 over the next week or two," Stovall wrote late Wednesday. "We think a break to new recovery highs will force some bearish investors to throw in the towel, adding fuel to the equity rally. We think the next big rally could carry the index up to 1,500+ over the next two months."

Of Draghi and the ECB, Stovall said he's expecting a rate cut, a plan to purchase short-term notes, and some clarity on how subordination issues will be handled with respect to the central bank's bond purchases. He doesn't think the ECB will introduce a yield-cap plan for the debt of countries like Italy and Spain though.

Stovall is expecting the Fed to come through with QE3 on Sept. 13 unless the August jobs report comes in much stronger than anticipated on Friday, and offered this take on the recent market mood.

"Investors appear to have frozen up like fainting goats, in response to nervousness over upcoming European and U.S. central bank announcements, the payroll report and potentially market-moving new-product announcements," he said. "Investors have a good idea of the likely outcome, but the lack of clarity keeps them on edge. As a result, the tug-of-war continues between the cautious fundamentalists and more optimistic technicians."

As for Thursday's scheduled news, the earnings calendar features Cherokee ( CHKE), Cooper Cos. ( COO), Hovnanian Enterprises ( HOV), Quicksilver ( ZQK), Smith & Wesson ( SWHC), and Ulta Salon ( ULTA).

Navistar International ( NAV), the heavy truck and recreational vehicle maker, is also slated to open its books on Thursday, and the average estimate of analysts polled by Thomson Reuters is for a loss of $1.36 a share on revenue of $2.96 billion in its fiscal third quarter ended in July.

The stock is down more than 40% so far in 2012, hitting a 52-week low of $19.90 on Tuesday. D.A. Davidson, which has a neutral rating on the shares, will be focused more on details about the strategic plan in the wake of the resignation of longtime CEO Dan Ustian on Aug. 27, rather than the actual numbers.

"Navistar may be facing a tough battle for market share as the company transitions to the new engine strategy," the firm said, adding that it believes the current situation is "too fluid" to expect the company to provide guidance for the fourth quarter.

Wall Street gets a raft of employment data to chew over ahead of Thursday's opening bell, courtesy the Labor Day-shortened trading week. The docket features the August job cuts report from Challenger, Gray & Christmas at 7 a.m. ET; the ADP employment change survey for August at 8:15 a.m. ET; and weekly initial and continuing jobless claims at 8:30 a.m. ET.

By the time the opening bell sounds, the revised opinions about how the government's August jobs report will come in should be trickling out.

The other data releases slated for Thursday are the Institute for Supply Management's services index for August at 10 a.m. ET and weekly crude inventories at 11 a.m. ET.

And finally, Warner Chillcott ( WCRX) was a big mover to the downside following Wednesday's closing bell after the Irish drug maker announced a secondary stock offering. The shares were last quoted at $12.76, off 10%, on volume of more than 700,000, according to Nasdaq.com.

-- Written by Michael Baron in New York.

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