But for the record it is called a Roth after the late Senator Roth who sponsored the legislation that established the Roth IRA.
This is essentially correct, but here's a bit more detail, with citation to authority:
Under the Constitution of the United States, both houses of Congress need to pass the same bill before it can be presented to the President for approval.
US Constitution, Art I, § 7, cl 2.
On June 26, 1997, the House of Representatives of the 105th Congress passed the Revenue Reconciliation Act of 1997, reported at
HR 105-148. This bill did not contain the Roth IRA provisions.
The Senate considered the bill on June 27, 1997 and it adopted an amendment that struck the entire text of the bill and replaced it by a different bill sponsored by Senator Roth, reported at
SR 105-33. Section 302(a) of this latter bill (page 79 of the report) proposed to amend the Internal Revenue Code to add § 408A relating to "IRA Plus Accounts", as they were called in the bill. The Senate passed this version of the bill.
In order to resolve the discrepancies with the House version, the Senate appointed conferees (including Senator Roth) to negotiate with the House.
CR S6786 (Jun 27, 1997). In the version of the bill that came out of the negotiation conference on July 30, 1997, the "IRA Plus Account" had been renamed to the "Roth IRA".
HR 105-220, *40 (page 56 of the PDF). As we know, this is the name that the account would retain in the enacted legislation, the Taxpayer Relief Act of 1997, PL 105–34, § 302(a),
111 Stat 788, 826 (Aug 5, 1997), codified (as amended) at
26 USC § 408A.