Final answer:
Abraham Lincoln increased his visibility to voters by engaging in debates with Stephen Douglas during the 1858 senatorial contest in Illinois.
Step-by-step explanation:
Abraham Lincoln used the campaign tactic of engaging in debates with his opponent, Stephen Douglas, to increase his visibility to voters. These debates, known as the Lincoln-Douglas Debates, took place during the 1858 senatorial contest in Illinois.
The debates were highly publicized, with newspapers throughout the United States publishing the speeches, allowing Lincoln to gain national recognition and raise his profile with both northerners and southerners. Although Lincoln ultimately did not win the U.S. Senate seat, the attention earned from the debates helped build momentum for his eventual presidential campaign.