For this purpose we believe in securing for the people the direct election of United States Senators exactly as the people have already secured in actual practice the direct election of the President.
Page 65: (February 21st, 1912)
I believe in the election of United States Senators by direct vote.
Page 315: (August 17th, 1912 - Bull Moose platform)
In particular, the party declares for direct primaries for the nomination of State and National officers, for Nation-wide preferential primaries for candidates for the Presidency, for the direct election of United States Senators by the people; and we urge on the States the policy of the short ballot, with responsibility to the people secured by the initiative, referendum, and recall.
As an aside note, I'd bet that many people didn't realize that all of these things were originally a part of the progressive program. All of this makes sense, when you consider the massive amounts of propaganda that progressives were putting out back in those days, and do still to this day.
There are a lot of people who will do a lot of hating on Woodrow Wilson for all of the things that were done on his watch(and almost the entirety of it is rightfully deserved. See my archives, I've probably posted about Wilson more than any other), but it's long been forgotten in far too many quarters that much of Wilson's program was either an extension of Roosevelt's or was the direct implementation of it.
At the time that these speeches of his were being given, the 17th would've been making it's way through state legislatures.
Now, it's true that there may have been more consistent voices out there agitating toward the implemtation of direct senatorial election, in particular, William Jennings Bryan. But as a former President, Roosevelt's voice would've been a powerful affirmative voice toward it's implementation given his popularity. And as the leader of the progressive party, Roosevelt's position on the matter should not be forgotten.