The written statement that Comey plans on reading to the Senate Intelligence Committee tomorrow has been released. You can read it here via the Washington Post. The last part of Comey's prepared statement is particularly interesting:
April 11 Phone Call
On the morning of April 11, the President called me and asked what I had
done about his request that I “get out” that he is not personally under investigation.
I replied that I had passed his request to the Acting Deputy Attorney General, but I
had not heard back. He replied that “the cloud” was getting in the way of his
ability to do his job. He said that perhaps he would have his people reach out to
the Acting Deputy Attorney General. I said that was the way his request should be
handled. I said the White House Counsel should contact the leadership of DOJ to
make the request, which was the traditional channel.
He said he would do that and added, “Because I have been very loyal to
you, very loyal; we had that thing you know.” I did not reply or ask him what he
meant by “that thing.” I said only that the way to handle it was to have the White
House Counsel call the Acting Deputy Attorney General. He said that was what
he would do and the call ended.
That was the last time I spoke with President Trump.
It's worth reading the entire statement if you have time. They clearly show that President Trump asked Comey to drop the Flynn investigation on multiple occasions, which would certainly qualify as obstruction of justice.