By David Lawder

WASHINGTON (Reuters) - Members of the Congress may not want a bruising government shutdown fight just weeks before November's elections but there are some early signs, worrying to senior Republicans, that they might get one anyway.

It would be instigated by fiscally conservative Republicans who may not go along quietly in mid- to late-September with a short-term spending extension necessary to keep the government running when the fiscal year ends at the end of that month.

These House conservatives don't want to give up hard-fought budget cuts already baked into House-passed spending bills - or worse - punt spending decisions into a post-election lame-duck session.

The September vote on a spending extension, through a continuing resolution, will be the last piece of must-pass legislation before the November 6 elections.

With the current round of partisan show-votes on extending tax cuts expected to be blocked by the opposing party, some lawmakers could see it as the final chance to make a point about spending and taxes.

"Since it's obvious that Republican leadership will do whatever it takes to pass a continuing resolution, conservatives are going to do what we can to limit the damage," said an aide to a conservative House Republican.

How far they will push things as the September 30 fiscal year-end approaches is yet to be seen.

"There will be definitely be some noise and probably a lot of smoke over a continuing resolution, but it's unclear that they'll want to light a fire right before the deadline," said Chris Krueger, a political analyst with Guggenheim Partners in Washington. "These guys will want to get home as soon as they can to make sure that they win their races."

Republican concern about a shutdown fight was reflected in a letter signed Wednesday by 20 House and Senate Republicans urging House Speaker John Boehner and top Senate Republican Mitch McConnell to seek immediate passage of a "fiscally responsible continuing resolution to extend federal operations well into next year".

"Taking the threat of a government shutdown off the table will allow a serious debate about tax and spending policy before the elections," the lawmakers wrote.

Fiscal 2013 levels for so-called discretionary spending, programs such as defense and education where Congress has more flexibility, were supposed to have been settled by the debt limit deal last year and the cuts it specified - to a $1.047 trillion discretionary spending level.

But House bills have cut $19 billion from that level, and fiscal conservatives are pressing for more. Campaign ads in congressional races feature claims about the need to tame runaway Washington spending.

SHUTDOWN BATTLE FATIGUE

Republican aides say House leaders have little stomach for last year's bloody shutdown battles that devastated Congress' approval ratings. Their plan is to pass a shorter-term measure sooner rather than later, pushing funding decisions past the election.

"There is a consensus that we want to avoid any big battle that could hurt (Republican candidate Mitt) Romney between now and the election," said a Republican House leadership aide.

This stop-gap effort would likely continue current spending levels or those agreed in last year's debt limit deal.

A fight over the length of the extension also is brewing. Some Republicans in both the House and Senate are insisting on a longer spending extension that goes into next year, when a newly elected Congress will take office. Continued...