* Possible U.S. government shutdown, lack of Fed clarity weigh
* World shares hold near one-week low
* German consumer confidence hits six-year high
* Oil above $109 as little thaw seen in U.S./Iran relations
NEW YORK, Sept 25 The dollar fell and world share indexes remained near a one-week low on Wednesday as concerns over a potential government shutdown in Washington and mixed signals on U.S. monetary policy kept investors cautious.
A vote is due in the U.S. Senate on a motion that will allow the government to keep running beyond the end of the month when budgets are due to expire, though lawmakers have yet to find enough common ground to ensure its passage.
A temporary spending measure would keep the government running after the Oct. 1 start of the new budget year.
Investors, wrong-footed by last week's surprise decision by the Federal Reserve not to begin trimming its bond-buying stimulus, are still debating the central bank's next steps and what mixed signals from policymakers say about the economy's health.
"Investors are not willing to sell the market only to see some kind of agreement reached that would give it support, nor jump in knowing it could get a lot uglier before it is resolved," said Rick Meckler, president of investment firm LibertyView Capital Management in Jersey City, New Jersey.
Meckler said there was confidence an agreement would eventually be reached, but "it seems we can't get out of the way of the political games that surround funding and operating the government."
The Dow Jones industrial average was down 14.54 points, or 0.09 percent, at 15,320.05. The Standard & Poor's 500 Index was down 1.65 points, or 0.10 percent, at 1,695.77. The Nasdaq Composite Index was down 8.15 points, or 0.22 percent, at 3,760.11.
The dollar was flat at 98.72 yen from late U.S. levels on Tuesday and down 0.1 percent against a basket of six major currencies.
The euro was firmer against the dollar at around the $1.35 level, supported by data showing German consumer confidence was running at a six-year high heading into October.
The MSCI world equity index, which tracks shares in 45 countries, was down 0.1 percent on the day.