Transcript for Senators to Investigate Possible Ties Between Trump's Campaign and Russia
This as new questions surface about why the president-elect's national security adviser has been in frequent contact with Russia's ambassador to the U.S. In recent weeks. ABC's Gloria Rivera is covering it all. Good morning to you. Reporter: This is a fast-moving investigation. Now the key concern here is whether or not repeated contact between a high-ranking trump adviser and Russia indicates the trump team somehow discussed or even helped shape Russia's response to those sanctions president Obama imposed after U.S. Intelligence officials determined Vladimir Putin ordered a hacking operation into the election. This morning, the republican-led senate intelligence committee launching an investigation into alleged lynches between Russia and Donald Trump's presidential campaign. The probe beginning just six days before trump takes office and as new details emerge about incoming trump national security adviser, Michael Flynn's contact with the Russian government. Flynn even seen seated next to Russian president Vladimir Putin during a dinner for the Russian TV station rt back in 2015. The trump team confirming Flynn texted with the Russian ambassador on Christmas day. Four days later they spoke by phone. The same day the Obama administration imposed sanctions for hacking and expelled 35 Russian diplomats. Trump spokesman Sean spicer tells ABC news the Russian ambassador invited Flynn to attend Syrian peace talks which the Obama administration has been excluded from. The fact that the designated national security adviser who has his own relationship with the Russian government was in touch with the Russian ambassador to the United States, I can understand why that was the subject of a column in the newspaper. Reporter: The Russian embassy won't comment on the phone call but confirms the ambassador will be attending trump's inauguration. According to the practice and protocol rules. Meantime, on capitol hill, FBI director James Comey taking heat from Democrats who after meeting with Comey say he hasn't done enough to investigate trump's alleged Russian ties. All I can tell you is the FBI director has no credibility. That's it. Reporter: Comey has been criticized for speaking publicly about the Hillary Clinton e-mail investigation days before the November election while staying silent about any inquiries into trump. Public forum we never confirm or deny a pepping investigation. I'm not -- The irony of you making that statement I cannot avoid. Reporter: Now he's promising to cooperate fully with an investigation into the handling of that case. The investigation will really try to hone in and determine whether or not Comey broke with justice department policy by commenting so publicly on the investigation so close to the election. Meanwhile, "The Wall Street journal" editorial board is calling for Comey to resign. If he refuses it's as president-elect Donald Trump should fire him. Paula, Dan. Gloria, thank you.
This transcript has been automatically generated and may not be 100% accurate.