The New Zealand dollar has gained as the deadline looms for US politicians to cut a deal to avoid a potential default.

The kiwi rose to 83.86 US cents at 5pm in Wellington from 83.67 cents at 8am and 83.31 cents on Monday. The trade-weighted index gained to 77.76 from 77.34.

Investors are becoming more optimistic US legislators will reach a compromise over the stalled federal budget, with a Thursday deadline looming for a deal to be reached.

If the Republican-controlled Congress and Democrat President Barack Obama can't reach a deal by then, the US faces defaulting on its sovereign debt obligations if it can't raise its debt limit.

"People do seem to think they're going to do something - what that optimism is placed on is not exactly clear," said Chris Tennent-Brown, FX economist at Commonwealth Bank of Australia in Sydney.

"The Aussie and the kiwi managed to lift against the US dollar, and both are near highs for quite a while."

Minutes to the last Reserve Bank of Australia meeting showed its board is still open to another rate cut if need be.

The kiwi was little changed at 88.01 Australian cents from 87.96 cents on Monday.

The kiwi gained to 82.56 yen at 5pm in Wellington from 81.89 yen and to 61.83 euro cents from 61.42 cents.