A cascade of Democrats facing competitive races backed an impeachment inquiry this week, which likely spurred Speaker Nancy Pelosi to drop her objections to using that word to describe ongoing probes.

Some vulnerable incumbents are not using the “I” word, however, and the Republican-leaning districts they represent help explain why.

These lawmakers are not defending President Donald Trump. But they want more information about allegations that he pressured the newly elected Ukrainian president to investigate a potential 2020 opponent, former Vice President Joe Biden. They particularly want to read the full complaint from a whistleblower who raised concerns about the president’s actions. Some also say an inquiry should be bipartisan, while one has questioned whether Trump’s actions rise to the level of impeachment.

Of the 44 Democrats named to the Democratic Congressional Campaign Committee’s Frontline program for vulnerable incumbents, 10 had not backed a formal impeachment inquiry at press time.

Most Frontline members took that step following the latest allegations relating to Ukraine, and more than a dozen went a step further to say that if proved true, the allegations would be impeachable offenses.