NEW YORK (Reuters) - Investors are hoping swift action on an economic stimulus plan will boost Wall Street this week after its worst January ever.

The stream of bleak news reached fever pitch after US companies shed more than 200,000 jobs in January and some investors worried a plan to shore up banks may take longer to come together.

The nation's recovery hopes have been placed squarely on the shoulders of lawmakers in Washington, where the US Senate will begin a closely watched debate this week on the $887 billion economic stimulus bill, after the House passed its version without a single Republican vote.

"If they come up with a plan — any kind of plan — the market will rally a little bit (this) week," said Warren Simpson, managing director at Stephens Capital Management in Little Rock, Arkansas.

But Simpson cautioned that without a plan, stocks could retest the November bear market lows. Indeed, David Kostin, Goldman Sachs' chief US equity strategist, said in a research note that the S&P 500 could challenge this low during the first quarter of 2009.

"Everybody's nervous here," Simpson said.

After a cascade of job cuts last week, investors are bracing for the government's January employment report expected Friday and the ADP employment data due on Wednesday.

Forecasts for the January unemployment rate hover around 7.5 percent, according to ThomsonReuters estimates. That would be the highest monthly jobless rate since September 1992 and an increase from December's 7.2 percent, Economists expect that US non-farm payrolls shrank by 524,000 in January.

Adding to the grim economic backdrop will be same-store sales expected from a slew of retailers on Thursday. Quarterly results from companies, including drug maker Merck & Co , mobile-phone maker Motorola Inc , and No. 1 U.S. home builder D.R. Horton , could confirm this snapshot.

"Everyone knows the numbers are going to be bad, but what we need to see is the direction policies are taking," said Eric Kuby, chief investment officer at North Star Investment Management Corp in Chicago. "Washington can change the tone of the market."

A broad rally among financials helped stocks early last week, but the surge was derailed on Thursday after data showed jobless claims scaled to a new high, while new home sales slid to a record low.

For the week, the Dow fell almost one percent, the S&P 500 declined 0.7 percent and the Nasdaq dipped 0.1 percent.

But the Dow and S&P 500 recorded their worst January slide in history. January performance is typically a harbinger for stocks for the rest of the year.

Financials will be a critical group this week as investors nervously await any news on President Barack Obama's alternate plans to prop up banks' balance sheets and the ongoing drama surrounding the economic recovery legislation.

"The fiscal stimulus package buys us time until the banking system is recapitalised," said David Joy, chief market strategist at RiverSource Investments.

Any delays in passing the package "would be a very big setback for the stock market, no question," Joy said.

Defaults on subprime mortgages led to losses on mortgage-related debt in the summer of 2007, triggering the credit crunch and wreaking havoc in the banking sector that led to the meltdown on Wall Street last year. The banking turmoil and the recession, which began in late 2007, have resulted in a sharp slowdown in bank lending and consumer spending, and a rising tide of job losses. The president hopes his stimulus package will mitigate the damage by helping the economy begin to turn around.

On Thursday, a slew of retailers will post same-store sales figures, which are expected to contract 2.4 percent in January. Excluding discount retailer Wal-Mart Stores Inc , sales could shrink 5.7 percent.

Investors will pay close attention to these numbers because consumer spending makes up two-thirds of the US gross domestic product, which shrank 3.8 percent in the fourth quarter — the fastest pace in nearly 27 years.

The US housing sector — the root of the economic crisis — will also be a focal point this week, although quarterly results from top US home builders, DR Horton and Pulte Homes Inc, and tomorrow's data on pending home sales may not yield many positives.

The week will kick off with a look at personal income and consumption, or spending, for December, plus the Institute for Supply Management's January index of US manufacturing activity, both due today. The ISM's January index of US non-manufacturing, or service-sector, activity is due on Wednesday.