THE presidential candidate for Senegal's ruling coalition, former Prime Minister Amadou Ba, warned on Friday that an opponent's proposal to introduce a national currency could discourage investors, a prospect the country could not afford. "Raising the debate around currency right now causes jitters among investors. Tomorrow, investors are going to wait and see before investing," Ba told journalists in Dakar. "Our economic and social situation does not allow us to create these kinds of uncertainty." Ba, 62, is facing 18 other candidates in Senegal's presidential election on Sunday. No frontrunner has emerged, but the opposition has seen strong momentum behind Bassirou…