The dollar struggled on Wednesday to rise from the previous day's six-week lows versus the yen and a one-week trough against the euro brought on by weak US data, as caution remained high ahead of other key releases.
Analysts have been expecting the August Institute of Supply Management index, due at 1400 GMT, to edge down to 60.0 from July's 62.0, and Tuesday's sharper than expected fall in the Chicago purchasing management index may have heightened worries.
A steeper than expected fall in the Conference Board's consumer confidence measure also hit sentiment on Tuesday, but investors remained cautious about selling the dollar aggressively ahead of Friday's US employment report.
"People are still waiting for this payrolls number as the big final important number that is going to prove the US economy is finally going to rebound from its slight slump and justify the Fed's actions," said Matthew van Dyckhoff, foreign exchange sales manager at Brown Brothers Harriman in London.
By 1130 GMT, the dollar managed to firm as far as $1.2156, up about a quarter of a percent on the day after weakening to $1.2194 on Tuesday. But it fell to $1.2180 later in European trade.
The dollar also traded 0.15 percent higher against the yen at 109.25, slightly above Tuesday's low of 108.71.
Some analysts said the dollar was also damaged by news that armed attackers had seized a school in southern Russia near Chechnya, taking 400 people hostage and threatening to blow up the building if police tried to storm it. The assault bore all the hallmarks of a Chechen rebel operation.
"The school siege is adding to the general terror worry," said a trader at a US bank in London. "People are starting to get a bit immune to these things, but you could add it into the stew, giving a bearish tone to the dollar."
The euro was little moved by eurozone manufacturing surveys, which showed the full bloc's index falling more than expected to a five-month low.
High raw materials costs, lacklustre domestic demand and weaker export growth stood behind the slowdown in manufacturing expansion. This prompted analysts to say that there were signs of eurozone growth having peaked already.