The retail industry has reported a 2.3% drop in sales as pre-election uncertainty and the timing of Easter dented figures for last month.
The latest snapshot from the British Retail Consortium (BRC) and KPMG revealed a partial unwinding of the 4.4% like-for-like improvement seen a month earlier, when sales were boosted by the inclusion of most of the Easter holiday.
The three-month average, which irons out Easter distortions, showed like-for-like sales up by 1.6% on a year earlier and by 3.8% overall.
BRC director general Stephen Robertson said: "There's no question customers are more willing to spend than 12 months ago but still nervous.
"People need to know how a new Government's moves to tackle the deficit will affect their incomes and jobs. Even if the measures are tough, knowing what they are could be better than the current uncertainty."
Non-food sales were affected by the earlier Easter and pre-election uncertainty as consumers favoured essentials and replacements over discretionary items.
The BRC said this meant a difficult month for firms in the electrical and electronics sector, with sales growth in larger items such as televisions and white goods often promotion-driven.
Clothing sales slowed - to their weakest growth since November - although this partly reflected tougher comparisons with a year earlier.
Womenswear trading held up well but men's and children's clothing slowed after two strong months.
The BRC added that footwear sales were in line with March but still weaker than previous months, while in homewares trading was below year earlier levels, despite further discounts and promotions.