PORTLAND, Maine — Republican U.S. Sen. Susan Collins and Democratic challenger Shenna Bellows will face off Monday night for a political debate that — if their recent forums are any indication — will feature sharp ideological contrasts and engaging oration from two masterful communicators.

After nearly 18 years in the U.S. Senate, Collins consistently receives the highest favorability scores of any politician in Maine, according to myriad poll results. All publicly released polls place her ahead of Bellows, the former executive director of the American Civil Liberties Union of Maine who is making her first run at public office.

Despite being deemed a major underdog by state and national political observers, Bellows has mounted a vigorous campaign that included a 350-mile walk across the state.

Previous debates between the two candidates have been marked by Bellows’ and Collins’ willingness to detail their positions and offer markedly different visions for what a U.S. senator from Maine can and should accomplish in Washington.

The CBS13/Bangor Daily News debate, which will take place in the television station’s Portland studio, begins at 5:30 p.m. It will be televised on CBS13 and streamed live at bangordailynews.com.