* Rand slips
* Stocks down led by Barclays Africa (Adds latest prices, analyst quotes)
JOHANNESBURG, May 31 (Reuters) - South Africa's rand weakened on Wednesday with a combination of mixed trade data and a looming interest rate hike in the United States keeping traders cautious.
Stocks were lower on the day with Barclays Africa unit falling after the company said it had approval to sell off its stake in the locally listed entity.
The rand weakened 0.4 percent to 13.1875 per dollar, sliding back from a brief run to a session best 13.0600 as a third consecutive trade surplus, albeit smaller than expected, failed to lift the cloud of political uncertainty.
"The short term outlook for the rand remains unfavourable as long as political noise continues to dominate headlines and drive pessimism," said economist at ETM analytics Halen Bothma.
The unit retreated from last week's 2-month high after President Jacob Zuma over the weekend survived a second attempt in six months by members of the ruling African National Congress (ANC) to unseat him as leader. It has been on the backfoot since.
Zuma has faced an internal backlash as well as outcry from opposition parties and civil society after his decision to fire Pravin Gordhan as finance minister in late March triggered downgrades to junk by two of the big three ratings agencies.
Fitch and S&P Global Ratings, who both cut South Africa's sovereign rating from BBB- to BB+ in early April are expected to make follow-up rating decisions this week, while Moody's is due announce a credit review in the next two weeks.
Trade figures for April showed the country recorded a 5.1 billion rand surplus, just shy of market forecasts. New vehicle sales and unemployment data are due on Thursday.
On the bourse, the benchmark Top-40 index fell 1.14 percent to 47,154 points while the All-Share index weakened 1.1 percent to 53,563 points.
Barclays Africa the biggest faller on the Johannesburg top-40 index, dropped 4.76 percent to 139.00 rand after its parent company Barclays Plc said it had secured approval from the South African finance minister to sell down its 50 percent stake.
Further losses came from retailer and wholesaler Spar Group which dropped 2.76 percent to 170.92 rand after its half-year slipped due to share issuance in part to fund foreign acquisitions and to settle its share schemes aimed at black investors.
In fixed income, the yield for the benchmark government bond due in 2026 was down 2 basis points to 8.6 percent.
Reporting by Mfuneko Toyana and Tanisha Heiberg