WASHINGTON — Tuesday’s vote in the House of Representatives to keep the federal government funded for two weeks is the first step toward averting a government shutdown starting Saturday, but it leaves the major differences between Republicans and Democrats over taxes and spending unresolved.

It also leaves tremendous uncertainty about what may happen next – whether the government will shut down later this month, or next, for want of funds, and whether the opposing sides ever can devise a long-term plan for reducing the national debt.

Tuesday’s vote is little more than “kicking the can down the road,” said veteran budget analyst Charles Konigsberg.

The House voted 335 to 91 to keep the government running until March 18, while cutting $4 billion. Voting yes were 231 Republicans and 104 Democrats; six Republicans and 85 Democrats voted no.

The Democratic-run Senate plans to vote today or Thursday on the two-week funding plan. Unless it passes, government funding runs out March 4.

The House last month approved $61 billion in cuts through the rest of fiscal 2011, which ends Sept. 30, but the Democratic-run Senate is unlikely to concur, leading to the two-week temporary solution while they seek common ground on the rest of the fiscal year.

Ultimately, the fight over short-term spending is the year’s first act in a more consequential drama – how to reduce federal debt over the long term. So far they’ve concentrated only on cutting non-military domestic discretionary programs that make up only 12 percent of the budget. They haven’t touched the big-money programs that drive up budget deficits – Social Security, Medicare, Medicaid and defense – not to mention possibly raising taxes to help end deficits.

But lawmakers face two looming deadlines: The federal authority to borrow will run out later this spring, and fiscal 2012 begins Oct. 1. Both deadlines will force Congress to confront tax and spending choices again.

The longer lawmakers deal with this year’s spending, the less time they’ll have to craft a serious plan to address long-term issues, observed longtime budget analyst Stan Collender. Another worry is that this short-term debate will stiffen both sides, making later negotiations more difficult.

“We’re frustrated that there’s such a hue and cry over a very small part of the budget. It reinforces the perception that the problem is just waste, fraud, and abuse,” said Robert Bixby, the executive director of the Concord Coalition, a budget watchdog group.